These tiny print beds are for the Tiny Prusa available here: https://www.prusaprinters.org/prints/146-tiny-prusa-i3-printer
by Dominik Císař.
I recommend you use my gcode made for the Mk3S but should also work on the Mk3. If you don't use my gcode you may need to adjust layer thicknesses at custom heights and add the color change yourself.
A blank bed is also included for making your own.
Attribution:
Adaptation of Adalinda by Louise Driggers - https://www.thingiverse.com/thing:246198
Adaptation of 3DBenchy by Creative Tools - https://www.thingiverse.com/thing:763622
Marvin by 3D Hubs - https://www.thingiverse.com/thing:215703
Josef Prusa's Buddy - https://www.prusaprinters.org/prints/62-josef-prusas-pug-buddy
Read above. The gcode has color change built in. Print the rest of the parts from the original.
The author hasn't provided the model origin yet.