In a thread on a guitar forum, I came across a DIY bass trap using these IKEA products:
IVAR System (using side-units, posts, shelves (regular or corner) & braces). Looks like a cheap and easy way (no cutting, etc.) to make a frame for your bass traps. Just toss in rock wool or compressed fiberglass (details about the specific type can be found in other threads here.) Cover the wool/fiberglass in your fabric of choice. Of course, you can paint the frame to your desired color!
I will likely redo my bass traps with these. Will look much better.

Paul