My HW99 was looking as bit bland as they all do when the open sights are removed (I bought it second hand and never had them unfortunately). So I designed a blanking plate I could make on a 3D printer, but also jazz up a little.
It's printed from a UV resistant material. Then chemically treated to increase strength, text painted, sanded and polished/waxed. The two pins on the bottom engage the empty screw holes and there's some double sided tape to keep it in place.
If there's any interest in them, I have a pile of unfinished ones that could be finished and put in the new items area of the sales.