cokin P lens cap

I tried to find these for a reasonable price, but either the item or the shipping made the cost too high. 

For the Cokin P type filter holder adapter rings. 

Leave the rings on your camera when you put them away. Provides good protection for the front element without requiring the removal of the P holder ring. Internal tabs secure the cap to the ring, preventing it from falling off in the bag or while carrying. When you want to shoot you can remove it with a simple pull, and start shooting. If you want to use a P filter holder you already have the ring attached. 

I printed this out of glow in the dark PLA. Looking for the ring in the dark of the night, or remembering to take it off just before sunrise should be less of a problem than with black plastic.