This instructable shows how to make an adapter in order to move your bike computer or the likes from the handlebar to the stem. I needed to do it because I run out of room on the handlebar, and it worked fine!
1) 1x wine cork (can be actual cork of silicone, perhaps another material - desirably lightweight and easy to work)
2) 1x tie-wrap (make sure the tie-wrap is long enough to accommodate the mount, the cork and the stem as in the image. 3) The existing handlebar mount for your bike computer/lamp/etc.
You can carry out these cutouts in a number of ways. I did it by drilling two 2mm diameter holes using a handheld portable drilling machine, and removing the material in between using a Stanley knife.
Carry out one cutout on each side of the mount.