Hey all! With the latest improvements in 3D printing, wasteless multi-color 3D printing is becoming more accessible than ever and so I've put together this guide on tips, tricks, and considerations for designing multi-color/material 3D models. I'm using the Bambu Lab H2C, Bambu Studio, and FreeCAD for this guide and its images. Slicer Painting Tips and TricksJust like we've done previously, we can paint our models in Bambu Studio using the Color Painting Tool:  Inside this tool, the best 'brush' to use is the Fill - Edge Detection. It allows you to hover over a section of the model and paint it to a color in one click.  You can see that the Fill tool painted a whole section that wasn't just one face, but a series of faces that had soft angles between them. You can make the fill more discerning by decreasing the "Smart Fill Angle" or make it select more by increasing that same value. Below, you can see that a low "Smart Fill Angle" selects just the one face, while a higher value selects the whole shoulder.  Sometimes, when I don't want to fill a whole face or the Fill tool isn't accurate enough, the Triangle tool is my next choice. It colors in a single face of the model like so: Multi-Body DesignIf you've designed models for multi-color before, you may have noticed that painting it in the slicer can be a bit tedious or that sometimes the way the slicer handles the painting isn't ideal.Here's an example of a simple paint that has an unsuitable overhang:  You can see that instead of full regular bridges, the left and right of the underside has floating overhangs.So instead of painting the model, I've made this design a multi-body model, where each part of the robot is a different body.  With this multi-body model, instead of painting, I can change the filament for one of the sub-bodies like so:  The painted model and the filament-changed model look the same in the slicer, but take a look at how they slice:  You can see the right model has clean straight bridges and won't have any drooping filament when it's printed. This is kind of 'painting' is much easier to do as well, if you've designed your model to be multi-body. You can go to the Objects tab in the left sidebar and right-click any sub-body to change it's filament:  There is one thing to note with this method, and it's that the order of the bodies within the model is important. The slicer goes top-down and 'creates' the first body, then 'creates' the next body. If the next body intersects with the first body, the first body will have the next body cut out of it. This repeats down the line, so the lower on the list a body is, the later it's 'created' and conversely the higher bodies on the list will have the negative shape of every other body cut out from it.This is important, because to achieve proper bridges and avoid other issues, certain bodies need to be lower on the list. In my example above, the 'waist' body needs to be one of the last ones, after the legs, to allow the bridges to be properly made. Fortunately, we can combine both types of painting at the same time! So you can block out a model and have its major parts painted by changing the filament of the body and then have details hand-painted in. So now you know why multi-body design is useful, but how can you do it?Creating Multi-Body DesignsI use FreeCAD for most of my designs, but most CAD software can export as a .STEP file. Exporting multiple bodies into one .STEP file will keep all those bodies relative to each other in space, but behave as one object in the slicer. You'll be able to go into the Objects tab again and see and work with the sub-bodies of the model.  If you use Blender, worry not, as you can do the same thing by exporting multiple bodies as a .3MF file. This can brought into Bambu Studio just the same with the result being the same as a multi-body .STEP file. Here's an example of a multi-body .3MF file that I've made using Gravity Sketch VR.  Hopefully this is a bit enlightening on how to approach multi-color design, and if you have any questions or comments, please let me know! Thanks all!