Frag plug fit-test coupon (free STL)
Every printer prints holes a little different: a 10.5 mm hole in the file can come out a few tenths small. The coupon measures yours. Print the strip, push one of your plugs into each hole, and tap the one that fit best.
Sign in free to download. It never uses a credit.
How it works
Your numbers, not ours.
ReefCAD saves the difference as your hole offset and adds it to every hole you make after that. The clearance pegs do the same for friction-fit lids. It’s free: sign in once and it never uses a credit.
What you can tweak
- Center size, range and step (10.0–11.0 mm by 0.1 mm to start)
- Wraps into two rows on small beds
- Sizes debossed next to each hole, or notch markers when text is too small to print
- Lid-clearance socket strip with loose peg tokens
Print tips
Print it right the first time.
Print it like the real part
Same printer, nozzle, filament and settings as the racks and jails you’re about to make. The coupon only measures what you give it.
Center it on your plug
The strip steps around the center size, 10.5 mm to start. Using mini plugs, large plugs or frag cups? Set the center to their size first.
Test with a few plugs
Plugs from one bag can differ a little. Try two or three in the holes you’re torn between, and pick the hole that takes all of them.
Read before you print
Frag plug hole sizes, and why fit matters
Plug stems vary by brand, and printers print holes a little small. Here’s how to find the hole that holds your plugs snug, without guessing.
How to 3D print a custom frag rack
From a tape measure to a rack full of frags: measure, calibrate, design, slice and print, with the settings that actually change the result.
FAQ
Fit-Test Coupon questions.
Yes. You sign in with a free account to download it, but it never uses a credit and doesn’t count toward your free exports.
Push the same plug into each hole and pick the snuggest one it still goes into by hand. In the app, tap that size under “Which one fit best?” and save. That’s your fit profile.
When something changes: a new printer, nozzle or filament can print holes differently.
More parts
Same fit, different job.
- Water Test StationOne home for your reef test kits.Reef water test station STL generator
Stop buying racks that almost fit.
Your tank, your plugs, your printer. Design it in a minute, print it tonight.