Corner Radius Guide 4 US Coin Sizes. Acrylic corner radius template. Cut from fluorescent green material for maximum visibility! I sometimes have customers who have used coins as a corner guide. This template includes Dime, Nickel, Quarter and Half Dollar sizes. These templates make it a snap (no pun intended) to accurately place a snap or rivet at the exact center of the corner radius. Eliminates the need for additional tools to measure and mark these locations.