3D Printing Chastity Cage: A DIY Guide for Engineers

A chastity cage is not a display model. It sits against skin for hours or days, takes bending loads at the ring, and gets cleaned often. That combination rules out most decorative print settings. Layer lines trap moisture and bacteria. Sharp edges from support removal cause chafing. A wall that looks solid on the slicer can leak through the shell once internal pressure builds.

The geometry is also unforgiving. The base ring has to pass over anatomy and then stay put. The tube has to align with the ring so nothing pinches. Small errors in diameter that you would ignore on a bracket become a comfort problem here. Even a 0.5 mm mismatch in ring inner diameter changes how the whole assembly sits.

So the question is not whether a desktop printer can produce the shape. It can. The question is whether the printed surface, material, and dimensional control are good enough for skin contact and daily wear. For a first fit check, often yes. For long-term use, that depends on the process you pick.

FDM with PLA or PETG is the cheapest way to test geometry. You can print a ring in 40 minutes, try it, and change the model the same evening. The catch is surface quality. A 0.4 mm nozzle leaves ridges that hold moisture, and sanding a thin ring evenly is slow work. If you print FDM, orient the ring so layer lines run around the circumference, not across the load path, and use at least four perimeters.

Resin printing gives a much smoother surface and holds small features better, which matters for lock channels and pin holes. The trade-off is post-processing. Uncured resin is a skin irritant, so the part must be washed, cured, and checked for tackiness before it goes anywhere near the body. Resin also gets brittle over time under repeated flex, and a cracked ring has sharp edges.

For either process, print a fit ring first. Ten sizes of a 5 mm thick ring cost less than one failed full cage. Once the diameter is right, print the tube. Keep the two as separate parts at first so a bad tube does not waste a good ring.

• 1
  FDMCheap, fast, repairable. Rough surface, needs sealing for hygiene.
• 2
  SLA/DLP resinSmooth and accurate. Needs washing, curing, and brittleness checks.
• 3
  Nylon (SLS or MJF)Tough and light. Porous surface, best with a smooth finish.
• 4
  Machined metalBest for long wear. Higher cost and longer lead time.

Start with the ring. Measure the circumference you want to fit and divide by π to get the inner diameter, then add clearance. A printed ring usually needs 1 to 2 mm more inner diameter than a metal ring because the surface has more friction and the material flexes less predictably. Round the inner edge with at least a 2 mm fillet; a square edge cuts into skin.

Tube walls should be 2.5 to 3 mm in FDM and 2 to 2.5 mm in resin. Thinner walls feel better but crack at the ring joint, which is where the load concentrates. Add a fillet at that joint rather than a sharp corner. Ventilation slots help with airflow and cleaning, but keep slot width under 1 mm if you want to limit access, and check that no slot edge is left sharp.

Metal design follows the same logic with tighter numbers. A machined ring can sit at the measured diameter plus 0.5 mm, because surface finish is Ra 0.8–1.6 μm and friction is low and consistent. Fillets can be 0.5 mm. Wall thickness of 1.5 mm in 316L or Ti-6Al-4V is stiff enough for the loads involved, and there is no layer direction to worry about.

There is no practical way to melt and fuse metal powder at home. Metal parts come from machines like LPBF systems that run inside controlled atmospheres with inert gas, and they need stress relief, support removal, and often electropolishing afterward. Attempting the same thing with a torch and a mold gives you porosity, which means trapped bacteria and unpredictable strength.

The other limit is repeatability. A one-off print that fits is fine. A second print of the same file six months later may shrink differently after a slicer update or a new filament lot. For a device that has to feel the same every day, that drift matters.

If the design has proven itself in plastic and you now want a part that holds its finish, cleans easily, and lasts, the sensible move is to send the model to a shop that machines or prints metal. A proven STL is a good starting point for that conversation.