Red Panda - Jumping Jack - Multicolor without MMU

I designed this baby toy, which my 5-month-old daughter loves.

With a total of 10 filament changes on the front part, it can be printed without an MMU or other material change system. The back part, as well as the limbs, are just a single color.

I printed it from Formfutura Reform rPLA, which is problematic with bed adhesion and warping for me, so I added a brim. With an MK4, you can go ahead and use the pre-setup file for PrusaSlicer. One drawback for me, the produced (b)gcode for the front cannot be invoked on the MK4 (Firmware 5.1.2) and freezes on print… But it can be sent via Prusaslicer with "upload and print" as a workaround… I have no idea what this is, and I opened an issue on GitHub for it… (Github Issue) 
If you want to slice it yourself completely, there is a guide below; except for the things stated below, all other settings are basically up to your choice as this is really straightforward with no overhangs or complicated geometry

I used the following filaments :

• Extruder1 - Formfutura Reform rPLA Caramel
• Extruder2 - Formfutura Reform rPLA Sangria Red
• Extruder3 - Prusament PLA Galaxy Black
• Extruder4 - Formfutura Reform rPLA White

In my file, the change order is: 

• Start on Caramel
• 0.2 – Red – Black – White
• 0.4 – Caramel – Red – Black
• 0.6 – Caramel – Red – White
• 0.8 Caramel

General Settings

• 0.4 nozzle
• 0.20mm Structural preset (speed should also work if your filament is working well on high speed)
• You need, of course, 2 Arms and Legs mirrored (right click - add instance - set as separated object, and then mirror along X-Axis) 

Assembly

Assembly is quite straightforward. 

For the limbs, just look at the build plate side, which is on the front of the result. The back plate needs to be turned around so the build plate side is on the rear of the model; there is also a little chamfer on the inner side to help center it. 

Assemble, as seen in the pictures, and best add the top hanger string before pressing in the backplate; otherwise, you can use a bent wire to insert that later, but doing it before is definitely easier.

Put the back plate on top and tap it hard into place with your hand. it should basically press-fit. The standoff should keep it from being too tight if your print tolerances are well enough… otherwise, loosen it by one layer.

for the lower pulling string, I use a 3mm cord, the lower knot is a Monkey's Fist, the upper one a simple Overhand Loop

Slicing for Multicolor on Prusa MK4

For the MK3s, it should work with the same settings but is untested.

I use a wipe tower, as otherwise I sometimes get small dots in my model after tool change; you could lower the purge mount probably as the filament change already purges almost enough, but as this costs me just 5 cents I actually don't care.

Prusaslicer in Expert Mode

• Printer Settings
  • General
    • Extruders: 4
    • Single Extruder Multi Material: Yes
  • Custom G Code
    • ToolChange G-Code:
      {if layer_num >= 0}
G0 Z+4
G X200 Y0 F4000
M600 ; change to filament for extruder {next_extruder + 1}
{endif}
      Note: the change to filament is just a comment in the g-code; you won't have it on the display when the change actually happens
  • Extruder 1/2/3/4:
    • Retraction
      • Optional (Wipe while retracting: yes)
    • Retraction when the tool is disabled
      • Length: 0mm
  • Single Extruder MM setup (important: otherwise, you get huge blobs on the wipe tower, which crash your nozzle!)
    • Cooling tube position: 0mm
    • Cooling tube length: 0mm
    • Filament parking position: 0mm
    • Extra loading distance: 0mm
• Print Settings
  • Multiple Extruders
    • Wipe Tower
      • Enable: Yes
      • Prime all printing extruders: No

Disclaimer

I have not tested any filament for food safety, nor tested if a child or baby could break the toy by chewing on it, nor anything in any safety realm.
So, use at your own risk, and in any case always watch your child when near the toy!