The basic idea here is to create a minimally sized yet durable case. I'd like to just make a clamshell case milled from Delrin. The PCB will be sandwiched between the top and bottom of the case at the 4 mounting hole locations. #3-48 screws will pass through the top of the case, the mounting holes in the PCB, and the bottom of the case (where they'll be secured with nuts).

The original design had built-in standoffs for the PCB, but I removed them to make it easier for Randy to mill a few.

NOTE: The stainless steel nylon-insert locknuts from McMaster-Carr have a 1/4" width and 9/64" height. The heads of the stainless steel pan head 1" long Philips head screws are .071" high and .193" diameter.

Bottom

from black 3/8" thick Delrin sheet:

Top

The case top is similar to the bottom, but deeper (1/2" thick Delrin). It also has notches cut in the side for wires to pass.

I bought 1.5" wide Delrin bar from McMaster-Carr. The .375" thick material is $6.81/ft, the .5" thick material is $7.99/ft.

Randy was gracious enough to offer to mill a few cases for me. I had raw materials shipped to his place. He sent me a picture of the initial hogging of each of the bars I sent him:

Randy soon finished the remainder of the stock I sent to him, and shipped me the completed cases.