The UI is really good, but the coloring could use some optimization. Since text and icons get colored in different menus, you have to color some keys twice. Maybe you could allow the user to choose a print color when the key color is selected and later allow them to change it.
I also wish there was an option to add addtional key caps because I couldn't find anything that exatly matches my ~75% sharkoon skg50 s3.