A few years back I started riding a bike to commute to and from work. I like to drink large cokes and iced teas so I felt the need for a cupholder that would fit my 64oz cup. None of the sport bottle holders I saw were even close, so I made a heavy duty cupholder for my bike out of a chunk of aluminum driveline. I used a discarded aluminum driveline from the scrap metal bin at work that was the correct diameter.
I started by disassembling the driveline, then I cut the piece for my cupholder from the driveline by cutting the tube 6 inches above the yoke end weld and cutting off the majority of the yoke below the weld. I ground down the yoke side to roughly 1/4 inch from the weld, sanded the weld smooth, drew a design pattern, and drilled many holes in the tube according to the design to make the cupholder lighter and more ornate. After drilling holes for the mounting bolts I bolted it to the bike frame.
Step 1: What You Will Need
A large diameter aluminum driveline, or something similar. A peice of PVC pipe with plug would work.
A cutting tool: like a recipricating saw, hacksaw, bandsaw, or chopsaw.
Angle grinder or die grinder.
A 2inch hole saw.
Drill, 1/4inch drill bit, 1/2inch drill bit.
Paper to draw the design for the holes to be drilled.
A felt pen.
A center punch.