Good point. Perhaps you can DIY a mini paint roller - I found this which I’m sure you can modify the roller with some felt, compressed cotton balls, or even erasers from a no.2 pencil. I just found these too. I’m sorry if I’m not understanding what you’re trying to achieve… if you’re worried about blots in the paint and the time suck, paint them in batches with a couple coats. You can even create a stencil out of a large piece of cardboard, just cut out 25 or so triangles, push the extruded part of the model through, and apply one or two coats of white paint with a small paint roller.