From the beginning, I've had a Humidity/Temperature meter inside the build chamber. Recent modifications have required it to be moved, and this thing is a mount to clip it to the top plate of the Replicator still within my hood. The previous thing was http://www.thingiverse.com/thing:25564 and the meter I used is here: http://www.amazon.com/Acu-Rite-Indoor-Humidity-Monitor/dp/B0013BKDO8/ref=pd_bxgy_hg_img_b

Simply slips on the edge of the top plate to mount the meter in the corner. The slip fit is probably OK, but if you want to drill a hole, there is accommodation for an M3 nut and M3-15 screw. The meter just clips to the upright part.