When gluing up a drawer, I needed corner protectors that were larger than the ones that came with my band clamp. So, I decided to make my own. The solution ended up being a section of PVC pipe that was left over from a plumbing project. After cutting the pipe into four pieces, I cut a 1"-wide slot along the length of each piece. The slot allows the PVC to fit over the corners of the project without damaging them. For clamping pressure, I used a standard band clamp.
The large diameter of the PVC allows me to stand the corner pieces on end and use both hands to center the strap.
The slot in the PVC makes it easy to reach a tape measure to the corners of your project and measure for square.