Ok, heads up, time to go re-download the files if you already downloaded them.
I found one transistor backwards (So test 1 wasn't working right), this has been rectified and the unit is now 100% certified as working by me (but that doesn't mean much... hahaha :D )
The aluminium plate behind the plastic plate can be easily constructed from some 1mm thin aluminium, 61mm x 120mm with 3.5mm holes in each corner (Measure against a plastic face plate to get their positions exact).
As Larry said, shielding is not an issue here so if a 3D printed part for the front panel was to be made, with the thickness of the now absent aluminium plate integrated into the 3D print instead, it might just be ok if you use a high infill percentage.
I've added add a STEP and STL file to to the files that will be able to be used for this purpose if someone wants to try it.
As for whether this was available for purchase from Tek as a completed product, I have a feeling this may have originally been a side project or similarby Warren Collier at Tek, and it must have worked well enough that the construction notes were released as a DIY type of thing.
Jared Cabot