The PVC pipe version is fairly simply, I used 3/4 inch schedule 40 PVC pipe for the holder. Cut to length of the battery(s) length - 1/4 inch (~6 or 7 mm). I use a spring (Digikey BCAA-ND, Battery Contact Spring AA) to help apply decent pressure against the battery. I use a screw (#6-32 Flat head) through the spring and through the PVC pipe cap. I only use a pressure fit currently but I have noticed that if I use flat end caps they have more surface area to hold onto the pipe itself.