Way back in September 2016, I asked about
daylight developing tanks for 2x3 sheet film and got some fantastic suggestions back. I spent a lot of time thinking about it, looking at alternative tanks, and shooting other formats and finally decided to get off my duff and use Sandeha's suggestion and build some homemade BTZS-style developing tubes.
So, a trip to the local home improvement store, a bunch of bits later, and I found myself in need of some rubber or rubber-substitute for the light trap. An unrelated plumbing emergency and I'm back at the home improvement store three more times, and now thoroughly familiar with the plumbing section.
The last trip was more leisurely, and I spot these things called "atrium grates" used to cap PVC or ABS plastic, and I had an epiphany. For about $6 USD I bought a single 3" atrium grate and fled the premises.
Once home, I broke out the hacksaw and the sandpaper and voilà:
I believe I can easily fit five sheets, six with just a little squeeze, and it should work for 6x9 cut sheet as well. There's enough play horizontally and vertically that I'm not anticipating development issues from the grate, but time will tell. I'll post results as soon as I have them.
I have to thank Francois for his inspiration, continually thinking out of the box and pushing us all to solve our own problems.