Build a hose adapter

Join two sizes nobody sells an adapter for — barbs, a hex grip, and a bore that is not a bottleneck.

This is the print that sells 3D printing to people: two things that should connect and do not, and nobody makes the part in between. A shop-vac hose and a tool port; a pond pump and a filter. **Measure the inside of each hose and aim a hair over.** A barb works by biting into the hose wall, so a barb that exactly matches the bore does not grip. This is the opposite of the clearance rule for parts that slide together, and it catches people who have just learned that one. **The bore is the number that matters most, and the easiest to forget.** It is the hole running the whole way through, and if you leave it at some cautious default you have built a bottleneck into the middle of your line. Take it as close to the smaller hose's inside diameter as the wall thickness allows. **The hex grip is not cosmetic.** Adapters get stuck in hoses; a hexagonal waist means you can get a spanner on it instead of ruining the part trying to twist it free. **Print it standing on end**, so the bore is vertical and the barb ribs come out as clean horizontal rings — on its side you would get a squashed bore and stepped ribs. For anything carrying liquid, add a couple of extra wall lines so it does not weep through the layer lines. Open Help → Build a hose adapter in the editor to build it hands-on, step by step.

1. Open the Generate panel and choose Hose / thread adapter.
2. Set End A diameter to 20 mm and End B to 12 — both ends default to a hose barb.
3. Set the Grip to Hex so you can get a spanner (or your fingers) on the waist.
4. Open the Bore to about 10 mm so the adapter is a fitting and not a restriction.
5. Run the print check, then export and print it standing on end.