Toy Excavator - Easy Bolt-Together Design

Overview

This is designed as vaguely compatible with 'misco' toys. I didn't quite match the threads so re-using the bolts probably doesn't really work. Other tools and pieces etc should work. I would recommend at least having the wrench (11/16" or 17mm) for the bolts. This is meant to be a resilient toy, that's easy to take apart and put together.

• The track idlers and undercarriage have a print-in-place bushing so the bolt can be tight, make sure your print tolerances are good enough that the bushing spins freely!

• Make sure to de-string and de-glob all the pieces as you print them!

• The main body piece has an engine cover that is held in place by magnets. You will need two 10x3mm disk magnets and some glue. The back should have just enough room to store a few extra bolts.

My vision for toys like these are to A) provide extremely fun mechanical experiences, and B) start building mechanical skills to provide an intuitive understanding of how things work later on.

Print Settings

I would strongly recommend printing in a strong filament like PETG. You really don't want these shattering. My recommended PETG for all parts would be:

• 0.15-0.2mm layer height

• 5-10% infill density

• 4 top layers, 3 bottom layers

• 3 walls

Support should only be required for the back cover piece. Print the tracks in TPU - I think softer the better. I've been using 85A.

Other

Tracks are based on/inspired by ProfessorBoot's design from his excavator. Files are designed in FreeCAD. I will post the source files after V1 is done. 

My TODO:

• [Done] ~~Finish body/undercarriage spacer~~

• [Done] ~~Fine-tune track tightness so they spin freely but don't fall off~~

• Add magnet-hole caps

• Future hopes: Add other bucket designs, blade attachment.

Updates:

• 11/15/25: Updated Arm1 model to hopefully have stronger threads & wider range of rotation for arm2

• 11/19/25: Updated main body to rev003; added thickness to areas over magnets, should be at least 3 layers now.

• 03/15/26: Added blade/pusher :)

DISCLAIMER/WARNING!

3D printed toys aren't super safe for kids! Stringing and over-extrusion can leave behind bits of plastic easy to eat, parts can break and leave sharp edges. Materials aren't vetted for being in mouths. I'm not a professional toy designer, I try and minimize sharp corners, but these models aren't perfect! They're also fairly heavy, wouldn't feel good if they got dropped on your head! These were never meant for babies, these are meant as a supervised play thing for at least somewhat dexterous kids. You've been warned. I won't be held liable.

Also, I can barely keep myself from playing with this thing all day. It's an excellent fidget toy too 👀