Why, for all the great Inanimate Objects downloads, of course! You can print emblems and costume details, as well as some Inanimate Objects playsets.
I’ve also used Photoshop to test ideas by making “virtual” customs. I’ll lay a figure on a scanner and scan an image of the (limb/head/chest/etc.) that I want to match to another scanned figure. This process doesn’t yield 100% results, especially since it only works in two dimensions, but it can give you a good idea of whether a proposed custom will work or not. It might just save you cutting into the costly rare figure!