I droped my MX Keys. It broke, well, no it still works but 3 keycaps got destroyed. A lot of searching around, they are too expensive on ebay, Logitech doesn't provide any spareparts. So I Reverse Engineered it and did some adjustments for 3D printing. 

I printed it out using a SLA printer and if the mechanic on those broken keys of mine, it would fit perfectly (Tested it on other keys). Of course I lost my newly printed key so I will post a Picture if I find it. 

This will not work on FDM printers (or will it?), since the smallest gaps on this thing are less then 1mm but with SLA it works finde (Tested on Elegoo Saturn 2 8k). 

I hope this helps :)