Bass Traps

The best I’ve seen that were DIY were plywood frames.
7-10 to layers of moving blanket were hung inside the frame and the plywood was flex seal. Pick your favorite fabric cover.

HF, MID glare and really helped with first wall reflection a great decay rates in the bass. VERY easy to manage with PEQ, DSP even a GEQ for bass only.

About 1/2-1" between the layers, don’t pack it.. MORE is not better.. AIR is actually better when layering.. Nothing I’ve see was better.

helmholtz resonator bass trap

They are a bit techier..

Master M.. He mad his own...

Buy a few rolls of R19, cover or wrap them, and place them in a corner of the room. 

Go to a hardware store and buy the cement round footing frames. You can get them in some very large diameter sizes and are made out of heavy carboard. Then drill many holes in it. Stuff it with mineral wool / insulation / fiberglass etc. and then cover the outside with fabric. Cap the ends with whatever- wood etc.
A cheap DIY project.

ozzy

Don't bother. They do not work.

Buy real ones.

Google Jon Risch bass traps. He shows his design in detail.
He can also be found over at audio asylum. He has been very helpful  over at audio asylum.
 I built two 20” traps per his design 10 years ago. Still using them.
Supposed to be similar to RPG traps.
joe