Coverite once made WW I vintage lozenge pattern covering, but it is, alas, long out of production. Monokote makes military flat colors and it wouldn't be too hard to cover with one color, prep and mask and spray another. Prepped correctly, paint will stick pretty decently to Monokote.
You can use 'Monokote Trim Solvent' to stick monokote to monokote. It comes in a 4 oz bottle. Works pretty well and you can use an iron to stick down the edges. Be real careful with large pieces. If air pockets form, they are a bear to get out.(Prick 'em with a pin) The trim solvent works really fast, push out from the center to the edge to avoid the 'bubbles'. Jerry