I've also been doing measurements as I build my Thunderpants knockoffs. I'm taking a slightly different approach in that I want my cups to be hot swappable, so that I can have different damping schemes for mood/isolation/weight. And just to have fun with different enclosure types. So I'm attaching the baffles to a DT880 type swivel headband and using a strap for cups.
I highly recommend that you guys get a hold of Room EQ Wizard (freeware) and a Panasonic WM-61a mic capsule ($3) to perform measurements. You just solder the capsule to the end of some beaten up earbud cord, short the ring and tip on the plug, and you have an adequate microphone for measurements that will also fit in your ear (inside an ear plug). REW does the measurement sweep and deconvolution for you, and you get to see the impulse response etc. I'm able to get good repeatability with these in ear measurements, and each measurement only takes a few seconds.
I want to get a damping scheme that is as close as possible to flat, according to the in ear mic, to use with binaural reproduction, and at least one more for diffuse field EQ. Maybe many more! My dad is a wood turning so I can order up different cup types and sizes.
As I get further along I'll post some pics.
I actually have a couple of technical questions for you guys as well. First up - what's a good PC oscilloscope? I want to check my square waves. At the moment I'm generating in REW, recording in Audacity, and looking at the waveform...but Audacity keeps crashing. So far I can't get the square wave to look totally flat at 30 Hz like the Thunderpants measurements at Inner Fidelity, but I can get a waveform similar to to measurement of LFFs pair. (Step rise and roughly linear fall to zero.) I'm wondering about the bass vent. In this case, the bass vent does not work like that of speaker system, right (constructive interference)? It's more like a pressure valve? In that case does the shape matter at all? Thunderpants have a single hole. What happens if that is replaced by a line with the same area (e.g. a thin circumference of felt)? And then the mathematical limit of a slightly porous cup?