Neat, good job. You might want to include what screw size it fits, and the word "anchor" somewhere in the description/title for searching (these are typically called drywall anchors in the US).
Fyi, it should work for screws with a diameter of ~3.5mm. As long as you can get the screw to self tap its own threads, you should be OK.
Everything should be a very tight fit, when all is said and done. I have to press the anchor bits into the cap by pressing the assembly together hard on my desk.