Here's my build of the Hexapod. I decided to go with red plastic because everyone always seems to build their Hexapods in black and I wanted to be different. I think the red gives it a more dramatic look too. For printing infill I used 100%, so this is solid plastic, not hollow, which gives more strength and for these thin parts it doesn't take much longer to print or use much more plastic. I'd guess the total amount of plastic was about 800 grams of PLA filament, about 4/5ths of a spool.
Like everything I build I used metric hardware, M3 button head screws in 8, 10, 12, and 16mm lengths. These work just the same as the weird imperial nonsense and have a nicer look. The mechanical build was fairly straightforward. Due to imperfections in the 3D printing process and the dimensions of the parts, I had to drill all the screw holes by hand, either 1/8 inch (yes I have imperial drill bits) so the M3 screws could pass through, or 3/32 for the screws to bite into. If I was designing these parts myself I would have adjusted the size of the screw holes so that no post-processing of the printed parts was required. With 420 screws it's a lot of drilling and screwing, so an electric screwdriver is a must.
I built each leg and then used a servo tester to make sure they were correctly aligned and working before the attaching them to the body. The servos were the LKY62 ones from Amazon, and when I bought then they were 5% off, which worked out to about $4.30 each. The 624ZZ bearings also came from Amazon as a pack of 20 for $12. I recommend getting ZZ bearings as they are sealed on both sides, unlike the Z bearings mentioned in the parts list, which are only sealed on one side. All the other parts are as listed in the parts list, and I shopped around for the best price. For example, the SBEC is best bought from HobbyKing to save a few bucks. You may need to epoxy the heat sink on, as the heat sink compound doesn't stick very well. I used red-blue bicolor LEDs instead of red-green, and I used 5mm LEDs instead of 3mm, but this makes them pack a little too tight and they don't quite sit in a straight line.
For the power switch I accidentally bought a switch much too large, 120v 20a, but decided to use it anyway. To mount it I printed an extra body riser, to be placed in the rectangular hole at the end of the body frame. I drilled a hole for the switch and cut the sides off and mounted the switch in it, then mounted the riser in the body and drilled screw holes to hold it. While mounting the riser in the Hexapod I wasn't paying attention and put it on the front instead of the back, but I wan't prepared to move it again, so the power switch is on the front face. For power supply I use the 2S batteries from my drone so they're interchangeable, and so I wouldn't have to buy another expensive battery just for this robot. Then I simply adjusted the battery levels in the software so the LED battery meter works appropriately. For the battery connector I used an XT30 plug rather than the XT60 listed, because these are what my batteries have, and they're rated for 30 amps, which is plenty for this build.
My biggest problem with the build was the PS2 controller/receiver. I bought a Logitech one as recommended on eBay but it didn't work, no lights on the receiver. I spent a long time troubleshooting but with no luck. So I bought another receiver but it also didn't work. I thought maybe I'd blown up my Arduino. In the end I gave up and bought a pack of two ultra-cheap wireless PS2 controllers brand new on Amazon, and the first one worked straight away. So I don't recommend buying used electronics on eBay, even if it says "tested".
The other problems I had were solder bridges on some of the perf boards. I was careful and used a multimeter to check my work on the power lines of these boards, as you don't want these creating a short circuit to the battery and potentially causing a fire. However I didn't check everything and had a solder bridge between the signal wires of a couple of servos on leg 4, which caused it to act strangely. That took a long time to troubleshoot and figure out. Also the LED board had a short which caused them not to work but I eventually found that too.
Also in my images for this build you will see a post-it note I made with the leg and servo numbering. This is important for the build, and if you look in the software you'll see the servo numbering, but it's not obvious, so I made my own diagram.
As regards software, I made some minor changes. I increased the step_height_multiplier to 3.0 so it would perform higher steps to get over low obstacles. I also changed the duration to speed up the Hexapod a little, from 1080 to 720 for normal speed mode and 2160 for slow motion mode. I also changed the LED battery limits for my battery as mentioned above, with values of 720 and 800, which correspond in my setup to 7.4 and 8.4 volts.
Here is a video of the final working Hexapod with a demonstration of the various gaits and modes.
Here are some ideas for future improvements and modifications. Of course, all of these would require major modification of the software, but since there are several Arduino Hexapod softwares already out there that implement some of these, it's mostly just a matter of putting the pieces together.