I posted this another site but thought it might be useful here as well.

I thought I would share my experiences with my DIY bass traps since it may help someone in the future.

Room's purpose is mixing/tracking.
Room's rough dimensions are 11' x 9' x 7.5' (small bedroom, low ceiling).
From reading thru the forums, generally speaking, effective traps are 4" thick with 4" offset from the wall --other factors includes position of the traps, the room itself, speaker placement, what I ate for dinner, etc.

NOTE: Some pictures may not necessarily correspond to text.

Cut to length frames from 1"x4" common board - attached w/ screws on end. I chose the cheapest and flattest boards available.
(REF: https://www.homedepot.com/p/1-in-x-4...3618/100025441 )
Frame dimensions varied but most common was a 2'x 4' (24" section is sandwiched between the 48" length boards).

Stapled screen (Phifer BetterVue Screen) to frame pulled tight across.
(REF: https://www.homedepot.com/p/Phifer-4...7671/202670858)
The screen is not necessary but provides better asethetics and simplified the upholstery process.
I completed 2 traps without the screen, but the insulation 'bulges' out in an unnpleasing way.
It became obvious to me that rigid fiberglass is preferred in this situation.

Flipped the frame over and place the insulation onto screen inside the frame. I chose the R-13 UltraTouch Denim because it was easy to work with and readily available, mostly a personal preference.
(REF: Shop UltraTouch R 13 77.52-sq ft Unfaced Recycled Denim Batt Insulation with Sound Barrier (15-in W x 93-in L) at Lowes.com).

Stapled remaining side closed using same screen material as mentioned earlier, but with less tension when stapling to frame since the backside of the trap is not visible and I didn't want to over compress the insulation.
(The insulation is generally about 4" thick but remember that the 1"x4" frame actual dimensions are .75" x 3.5")

Stapled front side w/ cheapest black fabric I could find from JoAnns, pulling it tight enough to get a clean 'flat' look. Cut off excess fabric as needed.

Screwed in 1.25" cup hooks into the ceiling joists and tied rope to length (somewhere between 2-3") with the #8 screw eyes (REF: https://www.homedepot.com/p/Everbilt...3682/204273860)
Quantity 4 per trap #8 screw eyes (with rope) installed onto panels before hooking onto ceiling. Spacing roughly same distances as corresponding ceiling hooks. I used a ladder for assistance when 'hooking' to ceiling.

I could not find (or I did not search hard enough) cheap and effective methods to create the 4" offset from the trap to the wall. Eventually I stumbled across 4" brace brackets (L brackets? Angled brackets?).
(REF: https://www.lowes.com/pd/National-Ha...ace/1000349847)
Added 7/8" cup hooks (REF: https://www.homedepot.com/p/OOK-7-8-...5544/203721766) to frame roughly 16" from top.
Added 4" scrap wood to the bottom of the panel to counteract the weight of the trap.

This creates the 4" offset from the wall with easy install/remove as needed, as long as the installation of the wall brace bracket holes align with the hook cup hooks on the trap.
I recommend screwing in the cup hooks onto the trap first, because that distance does not change. The brackets on the wall should be location dependent on the cup hooks.
The holes are big enough that the hook location can be forgiving but hooks should still be installed as accurate as practically possible.
The traps don't weigh that much so I screwed the brackets in straight into the drywall.

I used the ECM8000 from Behringer and REW software. I did my best to position both tests before and after with as close to the same settings as possible to develop the following graph:

Red - no traps
Blue - with traps

I do not claim this would hold up against scientific scrutiny but should still have some merit to demonstrate the trap's effectiveness.
Regardless of the data, the room sounds different. It's dry and flat. A few songs in and I could immediately hear the differences.
I can even discern left/right panning 'better' where as it sounded 'centered' at the listening position before the traps were installed.

It's been fun. I hope the information provided here is useful and helpful for anyone looking to build their own traps.
Thank you to the rest of the community for your valuable input on other threads and keeping the conversation going.