Diameter Corner mm Gauge Card

Corner Diameter Gauge Card (Metric)

This is a simple, card-style corner Diameter gauge designed to quickly measure the diameter of filleted corners by direct comparison. Just place the card against the corner and match the curve—no guessing, no math.

I designed this because most radius gauges available are stick-style tools that are easy to misplace. I wanted something flat, compact, and always nearby, like a business card.

Features

• Card-shaped design – lightweight, compact, and easy to store
• Metric units (mm) – clearly labeled on the model
• Measures corner diameter / fillets by direct comparison
• Great test print – perfect for checking:
  • Font clarity
  • Multi-color alignment
  • Small detail accuracy
• Easy to print – no supports required
• Multi-color friendly – designed so the text can be printed in a second color
  • Default colors shown are red on green, but you can easily change colors in your slicer

Why I Made It

I needed a simple way to measure the corner diameter of my keyboard while designing a custom case. Calipers and rulers work, but they’re slow and often lead to guessing. This gauge makes it easy to get an accurate radius for CAD modeling, especially when recreating existing parts. 

There are similar models for measuring object diameters, but I couldn’t find one focused on corner fillets, so I made my own.

Sometimes you cant measure half a circle, and can only fit 25% of the rounded edge. 

Use Cases

• CAD modeling & reverse engineering
• Measuring fillets and rounded corners
• Workshop or desk tool
• Quick reference gauge
• Calibration or test print

If you’re looking for a simple, practical diameter gauge that’s easy to print and hard to lose, this one gets the job done.