Allied Leisure Cocktail Tables backdrop

My cabinet has a 16:9 backglass screen and a full DMD, and I had this idea to make a mask to capture the vibe of the unique Allied Leisure cocktail tables (Take Five, Roy Clark The Entertainer, & Circa 1933). 

It's an interpretation of the octagon table design but liberties were obviously taken to make it work with the backglass.

I've included the .res I made to size the 3-screen backglass into this frame. You may need to make adjustments for your cab but hopefully this provides some clues on how I approached it.