Cup Holder Spacer

I have cup holders in my recliner arm rest, but sometimes I would like the surface to be flat to do crosswords, writings, etc. I designed this simple spacer to solve my problem, that can be easily removed for my evening cocktail. I'm new to 3D CAD design and printing, this is my first crack at publishing. The top outer surface measures 110 mm, the inner ring is 83mm.