I needed a platform on which the lamp socket could be mounted. Careful measurement of the original lamp holder, PH140 bulb, and the new bulb, suggested a level where this needed to be positioned. It’s very thick cardboard cut from the box my enlarger arrived in, initially held in place with nails pushed through the outside of the box. The large opening will have a thinner piece of mat or illustration board, cut with vents and a hole for the lamp socket to mount up. This will allow a bit of fine positioning before securing in place.