HUGE PROPS to WillsWorld for the original design. I just made a few easy mods to adapt this part for the newer shifters with reverse lockout.
UPDATE: The model has been printed & test fit. Like a freakin' glove. #caliperlove Inserting the letters requires a bit of finesse & just enough brute force not to break the R and X apart- just be patient & make sure to clear any wisps/stringing in the knob & the letters to make it easier.
UPDATE 2: As of January, 2019, this shift knob printed in PLA has been in my car in the Florida sun for well over 2 years. I do have 20% window tint all around (dark as legal in FL), but it gets plenty hot in my car & there was been no warping or softening of the plastic. Frankly, I am shocked. I figured I was going to have to re-print this in ABS or ASA by now. I did make this with 10 perimeters and 50% infill. I was still learning 3DP at the time, and way overcompensated, but it seems to have worked.
I recently purchased a brand new, shiny 2017 WRX. Months back, I had seen Joel Telling, the 3D Printing Nerd, print & install this shifter in his 2006 WRX, and I decided that I wanted to try it myself, just for something unique.
After failing to source the necessary hardware locally, I ordered on Amazon and then went to review the files before printing. And I noticed something was a little off. The original design was not intended for vehicles with the reverse lockout feature- the one where you have to pull up on a ring under the shift knob to access Reverse. In its original form, this shift knob would have essentially disable Reverse, because there needs to be a recess for the plastic bushing above the ring to pull up into.
So I went outside & took some caliper measurements of the shifter setup in my 2017 WRX (Same generation as 2015+), and apparently, the STi had reverse lockout with the same dimensions even earlier. If you have a pre-2015 STi, it's on you to verify dimensions, etc.
I then imported the files into Tinkercad and made the needed modifications. The visible mods are all on the bottom half of the knob. The shaft that extends below the sphere is wider & a tad longer to accommodate the lockout bushing. But the top half also changed, because the opening for the shaft of the shifter was too deep, and would allow you to screw he entire contraption down so low as to possibly block your reverse lockout mechanism, again killing Reverse. So I added a few mm of material to shorten the hole so that if you screw the assembled unit all the way down, it should bottom out just as the top of the lockout busing reaches the bottom of the shifter, leaving it free to travel into the recess designed for it. (Just like stock) Also added a small indent on the top piece for a Nylock nut to fit. (Many Nylock nuts have a ridge on top)
I did NOT make any changes to the WRX lettering. I will simply include those files here.
(1) m12 x 1.25 thread pitch Nylock nut.
(6) m3 x 20mm hex bolts
(6) m3 x .5mm Nylock nuts.
*Nylock nuts recommended. You could also use Loc-Tite, but make sure to chose the right variant of Loc-Tite so you don't permanently weld these things to your car. I don't remember the colors- I read the labels.
I was able to find all of these on Amazon, links below. These links are a public service only- I'm not getting an affiliate cut. And yes, these are for large quantities. Smaller quantities can be had on other web sites, but you pay a lot more per nut or bolt, and if you're 3D printing, you probably want these around anyway.
M3 x 20mm Hex Bolts, BLACK:
M3 x .5mm Nylock Nuts, BLACK:
M12 x 1.25 thread pitch Nylock Nuts:
Monoprice MakerSelect i3 v2.1
50% Fast Honeycomb (Simplify3D)
I have not yet printed my shifter, as my machine is busy with another print at the moment, but the settings above are my planned settings. Both halves of the shifter are oriented to print flat-side down, so they should not require supports or rafts on most well-calibrated printers.
Update 12 November: Printed shift knob, received all hardware, test fitted & drove 500 miles round trip Tampa to Miami and back with no issues. Lockout mechanism works with no interference, knob is solid. ***Note: Nylock nut needs to be super-glued into its recess in the bottom half of the unit, or the knob may be slightly loose when screwed into place.
A few extras...
The Nylock nut needs to be super-glued into place to make sure the shift knob doesn't jiggle on the shifter. I expected as much, and my test fit confirmed it.
The 20mm screws are just long enough for the job. You could go 25mm to ensure you're getting all the way through the nuts, but you might need to add washers if you don't want the screws to protrude out the bottom of the nuts. (I just got my 25mm screws in, have not tried them yet.
I sanded my finished print with 220 & 400 grit sandpaper, gave it a nice smooth finish. Not polished, just smooth. Also left the lettering looking like it is one piece with the knob. Very slick.
Also, sanded the flat parts of the 2 halves with 220 grit to ensure a flush fit.