Custom frag rack STL generator
Store-bought frag racks come in three sizes and none of them are yours. ReefCAD builds the rack around the space you have: set the width and depth and it packs in as many whole plug holes as fit, evenly spaced, with the leftover pushed into the margins.
Free to design · 1 credit per new design · Watertight STL + 3MF
How it works
Your numbers, not ours.
Holes start from your plug type (standard 10.5 mm, mini 8 mm, large 12.7 mm or 14 mm frag cups) plus your printer’s fit offset, so plugs slide in snug instead of rattling around or cracking the rack.
What you can tweak
- Width 40–400 mm and depth 30–250 mm, in 1 mm steps
- Grid, staggered, honeycomb or one row
- Max fit, an exact rows × columns count, or a fixed spacing
- Hole size, countersink and the gap between holes
- Flow slots between holes so water keeps moving
- Magnet back plate, rim hanger, end rails, printed-on, screw-in or PVC pipe legs
Print tips
Print it right the first time.
Calibrate with the same filament
Print the Fit-Test Coupon with the filament, nozzle and settings you’ll use for the rack. A new filament can print holes a little differently.
Keep the coupon as thick as the rack
The coupon’s strip and the rack both default to 5 mm thick. Change one, change the other, so a plug grips the strip the same way it grips the rack.
Measure before you drag
Measure the spot in the tank first, then type those numbers in. If the rack is wider than your bed, ReefCAD tells you before you export.
Read before you print
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.
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.
Choosing filament for saltwater tanks
What each common filament handles, what to keep out of a reef tank, and the print settings that matter more than the brand on the spool.
FAQ
Frag Rack questions.
With standard 10.5 mm plugs and the default 14 mm gap, a 200 × 100 mm grid holds 24 plugs. Switch to staggered or honeycomb and the count updates live as you drag.
Print the free Fit-Test Coupon first. It measures how your printer really prints holes, in 0.1 mm steps, and every rack after that uses the result.
Yes. Pick the magnet back plate and ReefCAD adds glue-in pockets sized to your magnets. You can also hang it on the rim, stand it on end rails or give it legs.
No. Racks print flat. Racks with legs print upside down so the legs grow straight up, and screw-in threads use 45° flanks that print upright.
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.