I picked this tip up from a recent White Dwarf, where they mentioned using a stick for priming. I typically use a sheet of cardboard with figures around the outside, which makes it difficult to get to the inside; or I used a strip of cardboard, which works well, but can't hold that many figures. A yard long, one inch square board of wood is just what I need, and I tried it out this morning with my Battlefront US Paratroopers which I'm finally getting around to painting. I really need to leave both ends free, though, and just put the figures in the middle. That would allow my to switch ends easily and spray from the other side. Now, in the White Dwarf article, they actually used all four sides at the same time, rotating the stick and spraying different angles. I'm just not that brave with my figures...
