Plugs for lines

Don't want to drain the mc, don't want to have to bleed it if it goes dry. Right now I have a yellow plastic wire nut in it. All plastic so figured it wouldn't hurt the threads if it's just finger tight. Still dripping a little so got a can under it but I know I'll kick that over at some point. Will try one ove the other ideas. Thanks!

If you have disconnected the lines, you're gonna have to bleed the entire system after you put it together anyway.

I have an old turkey baster that I use, suck the MC dry, blow the lines out and be done. Once back together bleed the entire system.

One major benefit is you will have all new fluid. That IS a maintenance item anyway, the system should be refreshed every 2 to 3 years anyway.