Surface Finish & Body Safety
The most important page on this site. Raw prints are not body-ready — here's how to fix that.
Why raw prints are a problem
FDM printing builds objects in layers, and the boundaries between layers are microscopic grooves. Those grooves trap moisture and bacteria and are effectively impossible to clean. Separately, filament is an industrial material: pigments and additives vary by brand, and almost none of it is certified skin-safe, let alone safe for mucous membranes.
Your three options, best to simplest
1. Smooth and seal
- Sand progressively — 220, 400, 800, then 1500–2000 grit wet — until layer lines are gone to the fingernail test.
- Seal with a body-safe coating. Platinum-cure silicone (the material used for actual silicone toys) is the gold standard; food-grade epoxy sealers are a second choice. Follow cure times exactly — uncured silicone and epoxy are irritants.
- Wash with mild soap before first use, and inspect the coating for nicks every time after.
2. Print it as a mold or sleeve core
Advanced but excellent: print the shape, finish it, then use it as a positive to cast a pure platinum-cure silicone toy. You get the printed geometry in a fully body-safe material.
3. Cover it
The honest shortcut: put a condom over the finished print, every time. It bypasses both the groove problem and the material problem for external and internal use, at the cost of elegance.
Filament choice
- PETG — our default recommendation: tougher than PLA, prints dense, sands well.
- PLA — fine for novelty and external items; brittle for anything load-bearing.
- ABS — sands and vapor-smooths well, but acetone smoothing must be done outdoors with real care, and residual acetone must fully outgas.
- Avoid mystery-brand filament, glow/composite filaments (abrasive additives), and anything with a strong smell when printing.
Structural safety
Print insertable designs solid or near-solid (4+ walls, high infill), inspect for layer cracks before every use, and retire any print that creaks, whitens at a stress point, or shows a split. Anal designs from our catalog all have flared bases or retrieval rings — that geometry is non-negotiable, on our files or anyone else's.