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

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.

Make sure you have enough depth, yet short the shelves in relationship to the support posts, which will help relieve connector stress and look a lot better, and scalloping those rear shelves will will assist in cable management. Make shelves a minimum of 19” wide. I prefer adjustable shelves to a accommodate gear changes and additions. Make sure to leave enough space for heat dissipation, especially above. While spikes and springs have their proponents, I prefer locking wheels Wheels will relieve torque stress on the rack and make changes much easier.

solid maple

HRS Nimbus couplers both sides, amp and floor. Walnut, sounds different….