Summary

Astro Boy! I included the 3mf for multicolor, or you can import the .STLs yourself. I used these round 3x1mm magnets, but really any you can glue onto the back of them. https://a.co/d/5ddhSyl

The STLs are all to scale with each other, but will need to be resized for your print.
For the size I arbitrarily chose these measurements.
X: 62.85 mm
Y: 75 mm
Z: 1.50 mm
astroboy-1.stl (Bottom) I made .7 mm for Z so it was thinner, and then dropped the layer so it was on the bottom.

Here are the colors I used from Top to Bottom:

astroboy-2.stl - Beige
astroboy-3.stl - Red
astroboy-4.stl - Green
astroboy-5.stl - Orange
astroboy-6.stl - Yellow
astroboy-7.stl - White
astroboy-8.stl - Black
astroboy.stl - Black

Double check the print preview. Some designs I have to paint on a layer of color. Let me know if you have questions. I'm still new to Multi-color and making my own models!