I just googled brush in capped bottles and there were some there, but not the big paint brushed you may be looking for. Maybe you can take a jar, punch a hole in the top, stick a med. paint brush in it then glue the brush to the top of the jar--or something like that.Why do you want the brush ih a cap? To keep the paint off your hands? If so, you can do the same thing with a plastic bag over your hands.

He is a plumber. No he is not worried about getting it on his hands.

He needs to paint some gas lines sometimes on the job. Obviously he does not want to make a mess in a customer's house, and it's always a small amount. And he is used to the brush in the cap because many plumbing glues come that way.

I had an idea today, about maybe a baby bottle and somehow sticking the brush through the nipple.

Worst comes to worst, I might by a bottle of school glue and dump it out and clean the bottle & brush.

I have seen it suggested somewhere to use empty shoe polish bottles for left over paint. to have it on hand if you need to retouch. might work for your husband to.

Woo Hoo!

Found some. I think I am going order the daubers too. He might like that better than a brush.

http://www.freundcontainer.com/screw-top-steel-cans/p/1905T09-B/