Found a good, simple read by Mark Sibole on making and using a focusing aid. Although the discussion centers around the Meade DSI line of cameras and their software, Envisage, I think it would apply to other situations also. Here is the
Link
This is pretty much a simple Hartman Mask I think, but hey, simple is good right?
I haven't tried it yet but I made up my diffraction spike mask last night since it was cloudy, again....
I improvised the materials and just used the side of a cardboard box and with the assistance of a compass, ruler, set square, electrical tape and a sharp knife. See picture.