This is the big brother of my 10 minutes robot, I wanted to make a keychain robot with a clasp embedded into it's head.
The end result is very nice but just a little too big to be a pocketable keychain.
I had to use supports or a brim with this model because the shoulders have a tiny buildplate connection area and wouldn't print without something holding them.
I printed in PLA, with support, 0.2mm layer height, 1.2mm shell, no infill.
The clasp is a "Lobster Swivel Clasps for Key Ring 37x16mm" from AliExpress, to insert it into the robot you need to stop the print at height 5.2mm (I used Cura's "Pause at height" plugin) insert the clasp making sure the ring isn't higher then the printed part and resume the print.
Designed with SketchUp, STL cleaned with Microsoft 3D Builder, sliced with Cura and printed on my Robo3D R1+ (I've added a "RepRap Discount Full Graphic Smart Controller" to my printer, pausing and resuming won't work on a stock Robo3D R1+ because you need on-printer controls to resume)
Update the V2 file makes the back of the knees and sholders flat, it isn't as nice as the rounded version but it has larger printbed surface area and is easier to print.