Casting your own silicone toy

From printed mould to finished toy. For adults (18+). Every fact links to where it comes from.

Read this first. Nothing in this guide or in the tool proves that a home-made toy is safe for use on or in the body. Skin-safe silicone, a clean mould and a good cure make it likelier, not certain. You choose the materials and you carry the risk. Sources for each claim: see the end.

• The process at a glance
• What the tool does today
• Choose the silicone
• Print the mould
• Prepare the mould
• Mix and pour
• Cure and demould
• Clean, store, use
• Materials and links
• Privacy and terms
• Sources

The process at a glance

1. Design. Draw the profile (thickness along the length) and the path (the line it follows). Fix anything the Checks panel marks. Start from a template if you like.
2. Build cast. Press Build cast, then download the two mould halves as STL or 3MF, and the print sheet. It lists how much silicone and filament you need.
3. Print the halves on your printer. Print the mould
4. Prepare the halves: clean, seal, release agent, do a test patch. Prepare the mould
5. Mix and pour the platinum silicone, slowly, from the base opening. Mix and pour
6. Cure and demould. Wait the full time before you open the mould. Cure and demould
7. Clean, store, use. Wash it and let it dry before the first use. Clean, store, use

What the mould looks like

What the tool does today

You draw the shape, check it, and download the object as STL or 3MF. The tool also tells you how much silicone to mix. Press Build cast and it designs a two-piece mould around your shape: a hexagonal block split along the centre line, with pins so the halves close one way, grooves for rubber bands, and vents where air could be trapped. Download the two STLs and print them. The steps from "Choose the silicone" onward apply to that mould, or to any mould you make yourself.

The size limits in the checks (5 mm radius minimum, 4 mm opening, 3 mm wall) are working defaults, not tested figures. They will be replaced by measured ones after a real print-and-cast run.

Choose the silicone

• Platinum cure, not tin cure. The two differ in the metal that starts the cure. Platinum types shrink less and keep for decades; tin types cost less. [Smooth-On FAQ 184]
• "Skin safe" is not "body safe". Smooth-On calls cured Ecoflex 00-30 and Dragon Skin 10 skin safe by an independent lab, gives no warranty, and leaves suitability to you. [FAQ 205] No page we read says such a grade is safe on mucous membranes, so this guide does not say it either.
• Read the labels carefully. USP Class VI is three animal tests on the material, pass or fail. It does not judge a finished device. [Elastostar] The US rule 21 CFR 177.2600 covers rubber for repeated food contact, not the body. [Cornell LII] Smooth-On itself says complying with it is not FDA approval. [FAQ 126]
• The trade runs on trust. "Body safe" often means only what the maker says, so ask for third-party test reports. [Dame] Pigments need their own tests. [SSP]
• Softness. Shore 00 is softer than A, and A softer than D. [Smooth-On] Dragon Skin 10 is Shore 10 A; Dragon Skin 30 is 30 A; Ecoflex runs 00-10 to 00-50. [DS 10] [DS 30] Pick from the datasheet, not from this page.

Print the mould

• Perimeters, not infill, give strength. Prusa: two perimeters minimum, three usual, four for strong parts; 10 to 15 % infill suits most models. [Prusa] [Prusa infill]
• Layer height. Thinner layers show more detail, taller ones show ridges; Prusa advises against going under 0.10 mm. [Prusa] We found no source for a best value, so test on your own printer.
• Layer lines show in the silicone. FDM moulds leave them in the cast. [Sinterit] [Formlabs] A filler coat such as XTC-3D fills the ridges and sands smooth. [Smooth-On] Both sources sell competing methods, so treat the size of the effect as theirs.
• Ironing the parting faces. Ironing is a second, slow pass over a flat top surface that smooths it; it does little on curved or sloped surfaces. [Prusa] The halves print with the parting face up, so it suits them. The Cast 3MF asks Bambu Studio for it (tick the box under Download). In any other slicer, switch ironing on for top surfaces yourself. Bambu Studio may show it under the object settings; check it before you print.
• The seam. Every FDM print has a vertical seam where each perimeter starts and ends. It can be moved, not removed. [Prusa]
• PLA and heat. PLA softens above 60 °C. [Prusa] Keep a PLA mould out of hot ovens and hot cars. We found no source for post-curing a cast in a PLA mould.

Prepare the mould

Do these in order: smooth and coat, seal, release agent. Run the test patch (step 1) on the finished surface before the real pour.

1. Run a test patch first. Platinum silicone will not cure against some surfaces, and that includes some 3D-printing plastics. [Polytek] Test on a small area: wall it off, pour, wait the demould time, then check for a gummy surface. [Polytek]
2. Know what stops the cure. Dow lists amines, sulfur compounds, tin salts and phosphorus compounds. [Dow] Sulfur clay, latex, polyurethane rubber and some paints are named too. [Polytek] Do not use sulfur clay in the mould, and keep tin silicone away from platinum. [FAQ 104]
3. Smooth and waterproof the inside (the author's method). After printing, sand the inside of both halves until the layer lines are gone. Then smear a thin, flat coat of UV-hardening resin over the sanded surface and cure it under UV light. The coat fills the layer lines and makes the inside waterproof and very smooth. Sand and coat every half, and keep the coat thin so it does not blur the shape or the pin fit. This step comes from the author's own casting, not from a listed source. Cure the resin fully: an incompletely cured resin surface can stop platinum silicone from curing. [FAQ 210] So run the test patch on the finished coat, not on bare print.
4. Seal, then release. A porous print needs a sealer, then a release agent. For PLA and ABS Smooth-On pairs XTC-3D with Ease Release 200. [Smooth-On] Give the sealer at least 30 minutes to dry. [FAQ 104] A sealer may not stop inhibition on its own. [FAQ 104]
5. Go light with the release agent. Too much causes pinhole bubbles. [FAQ 85] No page we read says release-agent residue is body safe, so wash the finished toy well.

Mix and pour

• Most Ecoflex and Dragon Skin grades mix 1 A : 1 B by volume or weight. [Smooth-On] The tool's Quantities panel shows part A and B for your shape. Always follow your own product's sheet.
• Mix A and B separately first, then combine, scraping sides and bottom until the colour is even. [Smooth-On]
• Work inside the pot life: 45 minutes for Ecoflex 00-30, 20 for Dragon Skin 10 Medium. [Ecoflex 00-30] [DS 10] Warmth shortens it, cold lengthens it and can stop the cure. [FAQ 136]
• Degas if you can. Skipping it leaves air pockets and surface flaws. [Smooth-On tutorial] The tutorial pulls about 29 inHg, lets the mix rise and fall, then runs a minute more. Thin, runny silicones may not need it. [FAQ 111]
• Pour in one spot at the lowest point and let it find its level. [Smooth-On] One hobby guide adds a thin stream, to avoid bubbles. [Instructables] That last point has only a hobby source.

Cure and demould

• At 23 °C Ecoflex 00-30 cures in 4 hours and Dragon Skin 10 Medium in 5. Dragon Skin 30 takes 16. [Ecoflex] [DS 10] [DS 30] Do not cure Dragon Skin 10 below 18 °C.
• Let it cure fully before you pull it. Very soft grades such as Ecoflex 00-10 cure with a tacky surface. [Smooth-On]
• Soft silicone can be turned inside out without tearing (Dragon Skin 10). [Smooth-On] The tool's 5 mm radius warning is a rule of thumb about thin necks tearing when you pull; it is not from a source.
• We found no source for a heat post-cure time or temperature. Do not invent one; ask your silicone's maker.

Clean, store, use

• Wash with liquid soap or toy cleaner and air dry. [Healthline] Health sites say silicone toys without motors can be boiled: 3 minutes [Healthline], up to 10 [WebMD]. Those apply to finished toys; for a home cast, ask your silicone's maker and use the shorter time.
• Store each toy apart. Non-silicone soft toys can melt into each other. [Healthline]
• Lube: water-based only. Silicone lube is not compatible with silicone toys. [Planned Parenthood Toronto] It can wear the surface and leave damage where bacteria live. [Healthline] One platinum-silicone maker says otherwise, so this guide takes the cautious view of the health sources.
• Anal use needs a flared base. It stops the body drawing the toy up, and without it an emergency removal may follow. [WebMD] [Planned Parenthood Toronto] The tool's For anal use box checks it. Do not shrink the base to save silicone.
• Do not switch a toy from anal to vaginal use without washing it, or without a fresh condom. [Planned Parenthood Toronto] Use plenty of lube; the anus makes none. [Planned Parenthood Toronto]
• Stop if anything hurts, tears or looks damaged. See a doctor if a toy will not come out.

Materials and links

You need: platinum silicone, mixing cups and sticks, a release agent and sealer, a vacuum chamber (optional), filament for the mould, water-based lube. There are no shop links on this site yet. If affiliate links are added, they will be labelled as advertisements at the start of the block, and you will still be told to read the datasheet before buying.

Learn more about silicone casting

Read on 2026-09-20; pages change. These are outside sites, not endorsements.

• Formlabs: casting silicone from 3D printed masters (manufacturer guide, from print to pour)
• Instructables: two-part silicone casting (hobby walkthrough with photos)
• Polytek: test cures for platinum silicone (how to run the test patch)
• Smooth-On: sealers and release agents (what to put on a 3D printed mould)
• Smooth-On FAQ: cure inhibition (why silicone stays sticky)
• Sinterit: finishing printed moulds for silicone (FDM, SLA and SLS compared)

Privacy and terms

• Adults only. The site asks you to confirm you are 18 or older, or of legal age where you live. It cannot check.
• Privacy. The site sets no cookies and has no accounts. Your designs stay in your browser unless you press Publish. Publishing sends the design file (the shape and its colour, nothing else) to the public gallery. The name you typed is dropped, and no personal data is stored. To limit abuse, Cloudflare counts publishes per connection address for a minute; the site does not keep that address. Published designs cannot be edited or removed by their author. The site saves three things in your own browser: your saved designs, your settings and the age confirmation. Clearing site data removes them.
• No guarantee. The tool and this guide come as they are. Shapes are checked against rules of thumb that have not been tested by a real cast yet. Nothing here is medical advice. You are responsible for materials, hygiene and use.

Sources

Read on 2026-09-20. Pages change; check the current datasheet. The full list, with what each page says and where the sources disagree, is in docs/GUIDE-SOURCES.md in the project. Health pages: WebMD (medically reviewed), Healthline (medically reviewed), Planned Parenthood Toronto. Manufacturer pages: Smooth-On, Dow, Polytek, Prusa, SSP, Mann. Retailer and hobby pages are marked as such in the text.