My primary mirror of my 8" telescope was made of molded recycled glass, as Pyrex is not available. Small bubbles in the glass wasn't any problem and the mirror came out very good. The tube was my only problem as I could not get the right size PVC tube. So, I decided to make my own. I used 4mm plywood cut in strips and riveted it on 2mm strips of aluminum. The tube was split in two so that the mirror would stand upright in transport. Four lockable clips was used to mount the two pieces together. The mirror was mounted so that it would be possible to move it backwards and forwards for taking photos.