Michal,
I had the same problem. I made mine. Tried melemine but didn't work, neither did the plastic inserts you buy thru the wood working magazines. I got a 1/4 piece of oak, traced out the outline and cut it out. I cut the recesses so it would fit flush by using the table saw blade like a dado blade, fine tuned the fit with a sander and it works great. I recommend using thin cherry rather than oak though. Cherry has a finer grain and is plenty tough. Can send you a picture if you like. Good luck Croft