I don't know if this is what Hoodaddy was refering to, but this is the jig I use.
Here is a jig I made and had good success with. I don't have a pic of the gill template, but you should be able to get an idea as to how it works. The mesh is replaced with a piece of plastic from a paper binder sleve. The gills or whatever else you want to paint is cut into the plastic. The plastic has a little slack, so when the top of the jig is down, the plastic wraps around the bait just enough to create a seal. Mark the location of each bait, keep it in the same spot for each bait of the same type and paint.The plastic cleans up well and can be used over and over. The bait is attached to a dowl and nail holder and slides into a hole in the side of the jig allowing two hands free for painting.
Attached Imagespics 001.jpg (65.1 KB, 75 views)pics 002.jpg (80.0 KB, 63 views)