Knob Adapter

So this is my metalworking project for today. I'm working on this shower with a jet tub in this  very old 3 story house in downtown Grand Rapids. It had a bad leak and the owner thought it was the faucet so I pulled off the paneling and drywall to get to the shower control and it is bone dry, This has an enclosure with 3 big mirrors and fluted wood dividers between the mirrors. I did not want to rip the whole thing apart( because I have to put it back together) so I cut off the fluted dividers 7" up and made new pieces that I encased in epoxy before installing. They were rotted at the bottom. ( most likely the leaking area). The paneling on the wall by the shower control was just full of  mold so it had to go anyway. I did not take any photos of the fluted pieces I made but I broke the center out of one of the knobs and have tried many different universal knobs to no avail so I took one of them and made an aluminum piece with the square pocket in it to go over the stem of the control and press fit it into the universal knob over the 2 lugs on the inside. 
The hard part was that the inner part of the handle had to fit inside a  chrome dress cover that is 1" inside. Most knobs were too big in that area. The Part on the left is from the universal handle and the metal part has to be fastened to the stem with an Allen wrench and it is inside the trim piece so even though I turned down all these parts to fit inside, I could not access those screws because the trim tube has to go on first!! Sometimes you think of things too late!
 It should be real easy to put this one on!! I did take some shots of the machining the square pocket:

I laid out the holes for the corners of the square in the mill

I drilled out most of the material for the pocket.

I milled the pocket with a 3/32" end mill and the little holes made clearance for the square corners.

Cheers, Jim