I designed the original version of this as a challenge to see if I even could. While successful (and vastly more popular and attention-getting than I expected by far) it had a lot of design issues. It was huge, took over a pound of plastic to create. It was fragile and wobbly, wouldn't stand up unsupported, and tended to fall apart if you picked it up wrong. Since then I've been completely redesigning it, to be simpler to make and more rugged, something that can actually be used as a toy, that doesn't cost a fortune to print.
This design is scaled to two-thirds the size of the original. It takes about one-third the plastic to print. It has about half as many parts, and is easier to assemble. The transformation sequence is simpler. Thanks to some interlocking tabs, the toy holds together very firmly both in robot mode and in Tardis mode. Due to the reduced weight and the redesigned joints, the robot easily stands on its own unsupported.
On the downside, it's can't be posed as freely as the original - there are a lot fewer axis of freedom in the joints, especially in the legs. That's the price you pay for something made completely of plastic.
This was actually a much harder design than the original - it's a lot harder to design a durable toy than something that just has to look right.
The toy stands about eight and a half inches tall in robot mode. In Tardis mode, it's four and a half inches tall, and two and a half inches wide. At 25% infill it takes 6 ounces of plastic to print, most of it blue.
As with the original, this toy can be built with entirely printed parts, doesn't need to be painted, and holds together without screws or metal pins. You can still optionally insert scraps of white construction paper in the windows to make them white, and print labels for the various decals. While it can be assembled without glue, I do recommend using a few dabs of glue on the locking tabs if you are actually going to play with it.
Original was printed on my custom Rostock derivative printer. Printed in PLA, using a 0.5mm nozzle and 0.3mm layer height, 2 shells and 25% infill. Autocad source files are included.
Transformation sequence, more pictures, and other details at http://drewsrobots.blogspot.com/2013/07/tardis-prime-version-2.html
I have uploaded plates of all blue, black, and grey parts. These should be able to easily print on a machine with a 200mm bed. In addition, you will also need to print the abdomen in white and the bowtie in red.
Major update on 7/11/2013: Slightly redesgined nearly every part for better printability and durability. Redesigned the elbow joint to keep the forearms from falling apart as easily and to make it easier to get it into Tardis mode. Got rid of the sliding black bar mechanism in the back, that idea didn't work out well, replaced it with two smaller fixed bars instead.
Added two thinner versions of the fist inserts in case you have trouble getting the standard ones in.
9/18/2013 update: I have modified nearly every part on the model to improve printability, ease of assembly, durability, and show-accuracy. Cleared up some issues with the leg and hip parts interfering and redesigned the fist sliders. It should be easier to assemble and look better now. I also rearranged the blue parts onto two trays that should be possible for any machine to print.
12/11/2013 update: Major tweaks for printability and easier transformation. I've added in a linkage between the abdomen and the head pivot so that the abdomen automatically slides up into the torso when the head pivots forward, and selective interference between the shoulder bars and abdomen mechanism to make the transformation process easier and more obvious. I eliminated all the fragile vertical tabs in the torso and shoulder blocks and made the shoulder ball-in-socket joint more robust. I have also completely redesigned the hips to make them easier to print and add a little bit of waist rotation. The legs and knees have been tweaked to stand more reliably and fit better together in Tardis mode. Also many other minor changes for durability and ease of priting and assembly.
The footleft, footright, hips, midback, torsobar, and bowtie pieces have optional versions with added support for more reliable printing if your printer has trouble with overhangs.
I have also now finally added parts for a Sonic Screwdriver gun. The parts for that are fairly fragile and difficult to print, so it's only recommended if you're confident in your printer's ability to print thin vertical pieces. It also has nowhere to go when the toy is in Tardis mode, but that's true of most transforming toys anyway.
Head and lamp:
In blue print:
In grey print:
In red print:
Optionally dot the eyes of the head core with a black Sharpie marker.
Press the head core into the blue head shell. Press the left and right head antenna pieces into the core through the holes in the shell. Depending on how tight your printer made it, you may have to glue these in, or it may be enough just to press them in.
Press the red bowtie into the slot on the head pivot. You will probably have to glue this in.
Do not plug the head into the pivot at this time.
Torso and shoulders:
In black print:
In blue print:
In grey print: (actually this can be any color, it's nearly impossible to see when everything's all assembled)
In white print:
1 torsobar_white (Note this piece is strength critical, use high infill when printing)
Identify the right and left back bars and shoulder bars. Note that the right and left versions of these are not identical, though they are mirror images of each other.
Carefully press the ball on the shoulder bars into the socket on the back bars. They should be snug but able to rotate and move in the sockets.
Press the head pivot piece into the groove on the torso cap block. You may have to pry the torso cap block open slightly while doing this to get it in. Be careful not to break it. Make sure you get the orientation on the head pivot correct, it can go in two different ways but only one is correct.
Optionally, cut eight pieces of white construction paper, 0.9" X 0.5", and slip them into the slots behind the window bars on the torso block and shoulder blocks. I have also provided the 'windowinsert' part which you can print and insert instead of strips of paper. This is useful if you want to make the window inserts some color other than white. You will need eight of them.
Press the torso link into the socket inside the torso block as shown. The flat side of the torso link should face forward in the torso block, and it should be able to rotate smoothly downward.
Press the clack chest bar into the torso block as shown. Pres the right and left shoulder bars into the torso block as well. Make sure you put them in correctly, there are small interference tabs on the shoulder bars that must face downward when they are installed or you won't be able to assemble the torso further.
Line up the holes on the bottom side of the torso cap with the tabs on the chest bar and shoulder bars and press it down. It should snap firmly into place. You should be able to easily rotate the shoulder bars forward and back.
Press the round cylindrical section of the torso bar into the C-groove on the head pivot link. This takes some care to get in without breaking.
Carefully pry apart the snap tabs on the torso bar and work it over the abdomen such that it locks into place. This is very tricky and best done in several stages, working the snaps into place one at a time. It should be able to rotate freely over a limited angle when in place.
Pry open the torso bar again and then press the open loop on the grey torso link into the opening on the abdomen. The snaps on the torso bar should lock into this loop and hold the three pieces together.
Finally, the base of the head pivot link snaps into the socket at the rear of the head pivot. When these are all together they should form a four-bar mechanism that links the rotation of the head pivot to the movement of the torso link, so the abdomen will rotate up into place as the head rotates forward. There is also deliberate interference between the torso bar and tabs on the shoulder bars so that swiveling the shoulders outward forces the head to pivot partially forward.
You can now insert the head into the head pivot. Note that it only turns about 45 degrees to either side. Make sure the torso transformation mechanism moves freely through its full range of travel at this point.
Press the shoulder blocks and shoulder caps onto the black snap tabs on the black back bar pieces.
Arms and abdomen:
In grey print:
1 fistleft_grey or
1 fistright_grey or
In blue print:
1 midback_blue or
Choose either the fists with holes or without depending on whether you want your transformer to be able to hold a gun. I usually print the right fist with a hole and the left fist without, but both versions are provided for both side. You should in theory be able to put any 5mm socket compatible gun or other accessory in these holes as well.
Two different versions of the midback part are provided. I find the version without support difficult to print cleanly, so I made a version with support manually added.
Press one elbow part into the lower side of each forearm. The elbow presses in flat from the bottom without rotating. Once in place it should easily rotate through 90 degrees.
Work the fists into the holes carefully. I use a set of needle-nose pliers to do this, working the piece in a little at a time on each side carefully. Note that once you get it in, the fist will be impossible to remove without breaking the forearm, so make sure you have the version of it you want.
Plug both arms into the shoulder blocks.
Finally line up the hole on the midback piece with the hole on the white abdomen part and push the abdomen pin through both pieces to hold them together.
In blue print:
1 hips_blue or
In grey print:
Two versions of the hips are provided. I find this piece looks better and prints more reliably with support, at the expense of a little extra plastic and cleanup time.
Line up the holes on each lower leg and foot piece. Drive a foot pin through to link them together.
Press one upper leg piece into the upper hole on each lower leg piece as shown. Note that the upper leg pieces are actually identical to each other, just mirrored for convenience, so don't worry about which is which.
Press the other end of each upper leg piece into the holes on the hips. You should be able to fold the feet, legs and hips together into a compact base of the Tardis as shown. This is a good point to check to make sure nothing is interfering.
Finally press the snap on the abdomen into the hole on the top of the hips.
The gun is a trickier piece to build than the rest of the model, as it has a lot of fine details and thin vertical pieces. You will want to make sure your printer is very good at printing finely detailed parts for this. You will also need to glue all these parts together, as nothing on the gun snaps together.
In black print:
In silver print:
In blue print: (I like to use a light translucent blue for these parts)
The blue tip and black barrel have extensive support material that needs to be very carefully cut away. After cleaning them up you can glue the tip into the end of the black barrel piece.
Push the blue core through the silver barrel, such that the skinnier part of the core protrudes from the tapered part of the blue barrel. The step between the smaller and the larger parts of the core should just line up with the end of the silver barrel piece. Dab a bit of glue around this point to hold them together.
Now dab a bit of glue around the indented flat parts of the silver barrel, and then carefully press the black barrel over the silver barrel as shown. The four black prongs on the black barrel should go over and catch on the flats of the silver barrel and lock the two pieces together.
Finally glue the left and right sides of the black stock together over the blue core. Once all the glue sets you have an assembled sonic-screwdriver gun.