I have sanding blocks of all sizes, most of the ones I have are great for large pieces of leather. Gussets, notebook covers, wallets, etc. 

But most are flat, or the curve is too big and challenging use when sanding small, intricate curves - especially on projects like passport wallets and watch straps. An example is the inner curve of this passport wallet, where getting a smooth finish can be frustrating.

Initially, I resorted to wrapping sandpaper around my thumb to work these small corners. This approach worked temporarily but became uncomfortable due to the heat generated during sanding. My next solution was stapling sandpaper around the ends of foam paintbrushes. You can see the picture below:  While effective, it was pain to replace the sandpaper each time, as the foam brushes needed cutting and restapling after every use.

This led me to design the Round Sanding Stick, a tool specifically created to make sanding fine curves easier and more efficient. What I wanted to include on the stick was to allow for quick and easy replacement of sandpaper while securely locking it in place. Here’s how it works:

• Design: The stick has a locking mechanism at the bottom and top that slides into place, holding the sandpaper securely.
• Sandpaper Dimensions: The sandpaper needs to be 50mm long for a proper wrap around the stick. The sticks fit together and leave a 0.75mm clearance to ensure a snug fit. (Most sandpaper is .3 to .8)
• Dual Grit Use: I often wrap two types of sandpaper: 800 grit and 1000 grit - on the stick, allowing me to switch between finer and coarser sanding as needed.
• Applications: These sticks are perfect for sanding small leatherwork details, such as watch straps, inner wallet pockets, and curved edges on passport covers and wallets, etc. 

This is mainly to solve a problem that I had in my projects. I figured someone else may have had a similar issue, so here we are.