A 3d-printed model may seem like it's already perfect as-is, but to really bring it to life one must add a splash of color to the model! It may seem like a daunting task, but in reality it's much easier than it may seem, seeing as it only needs 5 materials. That's right only 5!
For the model displayed above, I used a website called thingiverse to find a model of Thanos. The link to that model is in the materials below.
Red, blue, yellow, white, and black acrylic paint
A 3d-printer (the one I used for this model is the Qidi X-one, https://www.amazon.com/QIDI-TECHNOLOGY-New-Generat...)
Plastic cup (to hold water)
Step 1: Perfecting the Print
Before even adding color to the print, you must first sand down the entire print. This way the paint will actually have a chance to stick to the print, because otherwise it would fall off much easier.
First go around the print and look for areas of mistake, and sand those down. After this go to a higher grit sandpaper (if you don't have too high of a grit, then a low grit will work fine) and sand all areas of the print. Be sure not to use a sander, or a sanding wheel, seeing as those may melt the print, because of PLA's low melting point.
Step 2: Preparing the Paint
When painting be sure to use a mat of some sort to cover your table as to prevent paint from ruining said table. Be sure to fill your cup with water 3/4 of the way (doesn't have to be 3/4 full, just not too close to the brim so it doesn't spill). Having a paper towel handy would be helpful to dry off the paintbrush.
Step 3: Painting the First Layer
When painting models, I would highly advise going from the big areas, and then making your way to the smaller areas. What I mean by this is working on the larger background surfaces, and then adding in the details. For example in the picture shown above, I first colored in the head with and overall color of indigo. This is so that if I make any mistakes, it is really easy for me to go back over them in the net steps. When applying the paint be sure to keep dipping your brush in water, to keep the layers thin, and don't be afraid to go back over previous layers.
Step 4: Putting in the Details
After applying all of the overall color to the large areas of the print, you should color in the details. Use a smaller paintbrush (for convenience, if you don't have a smaller one this process will work, but will be harder) and go over the details. When doing this, be sure to smoothen the paintbrush on your pallet, so globs of paint don't drift into other areas of the print.