Seeking recommendations about material, design, makers of low-lying rack for gear

Size and Weight?

My surround/stand can support up to 125 lbs each, 3 optional heights

https://systems.audiogon.com/systems/9703

You can use any locally made top in lieu of the glass

I have another solution for larger, very heavy amps, I would need to confirm component availability if needed.

Nothing weighs very much. Light line stage preamp, DAC, streamer. Amps about 31 lb each but they'd go on platforms.

Two pieces of mdf or maple or combination of each. Use springs between the wood platforms. If you need leveling, add adjustable spikes under the bottom platform.

Maple is very inexpensive as wood goes. It is a bit of a PITA to work with. It is hard and the grain can be squirrelly. Any local cabinet maker can make you maple slabs which you can put feet on and use as amplifier stands. You can make an equipment rack by taking maple ( or any other wood. I like Cherry) slabs drilling a 1/2" hole in each corner. Then using 1/2" threaded rod and pvc pipe (as spacers) with the associated nuts and washers stack the slabs. Put adjustable feet on the bottom and you are good to go. You are not using a turntable so there is no reason to spring load anything. If I were to make it a two level "low boy" rack in 8/4 maple finished in catalyzed lacquer  would cost you in and around $400 complete. I am not for hire just using myself as an example. 

Thanks for the advice! No way I'm doing this myself. Too much going on. But I'd like to toss the job to a really good local craftsperson.