I just made mine out of scrap plexiglass. A hook or 'J' shaped piece out of strips that hung over the side of the sump, then a flat piece with holes drilled in it that the probes sit in that keep the tops out of water level and the probe under water.
I could take a pic if you are interested. It is quick and not that pretty, but no one can see it in the back of my sump.
Ingredients and tools:
scrap plexiglass
circular saw (for cutting plexiglass)
some sort of weldon for gluing plexiglass
drill for making holes for probes.
Time to make: ~10 minutes