DIY Active Ground Box

I recently received a custom cable that has three loop-ground spades that are linked to the cable's shield. The cable was originally designed for phonograph use, but my customized version is being used in a digital to analog function. The manufacturer left the loop-spades in. The manufacturer said I could just use electric tape to "cap them off."   The ground cables are not 100% necessary in this application. However, they are an exposed conductor. I know that I can enhance their performance by treating them as a floating shield by using an active ground.

I was thinking it would be cheaper and more practical to make my own. Does anyone have experience doing this? If so, can you share your design ideas?

The concept I have seen and want to build on, is making a wooden box that is coated internally with copper plates. Then use an IEC C14 socket to attach the ground lead to the copper plates via a solid copper cable.  Then create a simple plug using a NEMA 1-15 connector where only the ground lead is connected.

Then insert banana plug sockets that also attach to the copper plates via a copper cable. Then connect the spades to the banana plug outlets.

Once this contraption is plugged into the wall socket, it should effectively attach to the house's ground.

Thoughts?