Oculus Rift tactile keyboard tops

I've experienced the 3D virtual reality googles Oculus Rift now for 4 weeks and had one particular problem:
How can I find the correct key that I need on my keyboard when I don't see anything?

So I came up with a cheap €12 USB numerical pad and some on-top keys which have clear differences in haptics and feelings.

I simply glued those onto the numpad and voilá here is my low-cost Oculus Rift tactile keyboard. Simply configurated the most common commands to the respective keys and practic