I'm not going to get too specific with measurements here, since my goal was to make a one size fits all dispenser. I just took all the rolls of tape I had lying around and put them next to each other and added significant length to accommodate the tape I had and allow for some additional roles of different types in the future. The fat tape types like duct tape, packing tape and painters tape all have a hole in the middle that will be accommodated by the 3" pvc, and the electrical tape and tapes with a similar sized central opening will be taken care of by the 1.5" PVC... look at the picture, understand that the two types are separated by ~1" and adjust to accommodate whatever tape you have lying around plus some. Cut a bottom piece long enough at the full width of the fence slat. I made mine 22" long.