The short answer: if you need custom molded silicone parts made in the United States, the right company depends on volume and market. For medical and automotive LSR at volume, SIMTEC Silicone Parts in Florida is the only molder we read that states ISO 13485 and IATF 16949 together. Extreme Molding in New York states ISO 13485 and FDA registration and is the only one that says when its first article clock starts. For fast prototypes, Konark Silicone Technologies publishes 1 to 1,000 parts in 3 business days and tools from $1,295, and Rubber Industries publishes steel prototype molds from $850. For silicone gaskets and compression molded parts, Stockwell Elastomerics publishes its tolerance classes and durometer range. Almost none of them publish a minimum order.
We built this comparison by reading each company's own website in September 2026 and recording what it publishes about minimums, tooling, lead times, tolerances and certifications. Where a molder publishes nothing on a point, we say not stated rather than estimate it. The full buyer's guide behind these figures, including why the tolerance class and the material call-out belong on your drawing, is on our rubber molding companies and custom rubber and silicone molding page.
Silicone manufacturers vs silicone molders: who you actually buy parts from
Search for silicone manufacturers in the USA and the lists mix two different kinds of company. Dow, Momentive and Wacker make silicone itself: the raw liquid silicone rubber, high consistency rubber, fluids and sealants. They sell material by the drum to manufacturers. They will not mold your keypad or your seal. The companies below are molders. They buy that material, build a mold to your drawing, and ship finished parts. If you have a part number and a quantity, you want a molder, and the material maker's name only matters when your drawing specifies a particular grade.
Nine US silicone part manufacturers, compared on what they publish
| Company | Where it molds | Tooling or minimum, as stated | Lead time, as stated | Best for |
|---|---|---|---|---|
| SIMTEC Silicone Parts | Miramar, FL | Not stated | Not stated on capability pages | High volume LSR, 2-shot, medical and automotive |
| Extreme Molding | Menands, NY | Not stated | Molds in 3 to 12 weeks; first article within 3 days of the mold arriving | Medical LSR with a plannable first article date |
| Konark Silicone Technologies | Anaheim, CA | Tools from $1,295 | 1 to 1,000 prototypes in 3 business days | Fast prototypes and bridge volumes, all made in California |
| Rubber Industries | Shakopee, MN | Steel prototype molds from $850 | Prototype tooling typically 5 to 15 days | Prototype tools in steel, ITAR work |
| Stockwell Elastomerics | Philadelphia, PA | Not stated; common runs 500 to 20,000 pieces | Not stated | Silicone gaskets and compression molded parts |
| Protolabs | Maple Plain, MN | Molds from $1,495 on its injection molding page; without MOQs | LSR parts in 15 days or less | Quick-turn LSR with an online quote |
| Xometry | Network, domestic and international | Not stated | LSR from 15 business days | One quote across many shops, if origin does not matter |
| Apple Rubber | Lancaster, NY | $1,000 per manufactured item; $100 per stock line item | Not stated | Seals and O-rings to an ASTM D2000 call-out |
| Robinson Rubber Products | Minneapolis, MN | Not stated | Not stated | Custom compounds, LSR and overmolding |
SIMTEC Silicone Parts: the certified choice for LSR at volume
SIMTEC in Miramar, Florida is a liquid silicone rubber specialist running LSR, LSR 2-shot with thermoplastics, and multi-shot molding. It states it is ISO 9001, ISO 13485 and IATF 16949 certified, and it runs Class 8 clean room molding. Of the 16 molders we read, it is the only one that states IATF 16949, the automotive quality standard, which makes it the obvious first call for an automotive silicone part. It publishes no minimum, tooling price or lead time on its capability pages. That is typical of a volume molder, which prices every program from the drawing.
Extreme Molding: the only one that says when the next clock starts
Extreme Molding in Menands, New York states ISO 9001:2015 and ISO 13485:2016 certification and FDA registration. Its FAQ is more useful than most: it can source low-volume molds in as little as 3 weeks and high-volume production tools in as little as 12, using North American mold makers, and once a mold arrives it aims to mold first article parts within 3 days. It also publishes the life you get from each tool, around 25,000 cycles for a low-volume aluminum mold against 500,000 or more for a steel production mold. That single line tells you when a cheaper aluminum tool is the right buy.
Konark Silicone Technologies: published speed and a published tool price
Konark in Anaheim, California states that all of its manufacturing is done in California, which matters if your part will carry a made in USA claim. It publishes the most specific speed claims in this group: 1 to 1,000 silicone prototypes within 3 business days and 1,000 to 25,000 parts within 15 business days, with tool prices starting at $1,295. It lists a durometer range of 5A to 85A, much softer at the low end than most, and it names all four ARPM tolerance classes. It does not name certifications on the pages we read, so ask for them if your market requires them.
Rubber Industries: steel prototype tools from $850
Rubber Industries in Shakopee, Minnesota publishes the lowest tooling floor we found: steel molds starting at $850 for its prototyping services. It is specific about the metal, 4130 steel rather than aluminum, and about timing. Prototype tooling typically takes 5 to 15 days, production tooling typically 2 to 5 weeks. It states ITAR registration and ISO 9001:2015, and it molds silicone, fluorosilicone and LSR alongside EPDM, nitrile, FKM and other rubbers from more than 2,000 formulas. For a defense program that needs a real steel prototype quickly, it is the first call.
Stockwell Elastomerics: silicone gaskets, with the tolerance class in writing
Stockwell in Philadelphia is a silicone gasket and compression molding specialist, and it publishes the engineering detail other molders keep off their sites. It states that its molding tolerances are typically RMA A2 precision and A3 commercial, that it inventories silicone compounds from 25 to 80 durometer Shore A, and that its most common production quantities are 500 to 20,000 pieces. It also publishes shrink rates by hardness and LSR cure times of 30 to 120 seconds. If your part is a gasket or seal and you want to know in advance what precision to expect, start here.
Protolabs and Xometry: instant quotes, different trade-offs
Protolabs in Maple Plain, Minnesota states LSR prototypes and production parts in 15 days or less, standard silicone in 30 to 70 durometer, and ISO 9001, ISO 13485, AS9100D and ITAR. Its injection molding page states molds from $1,495 and parts on demand without MOQs. Xometry states LSR starting at 15 business days with 24-hour quotes and design for manufacturing feedback, and the same certification set plus UL. The difference is the model. Xometry is a manufacturing network and states domestic and international production, so ask which shop will run your part if origin matters. With either, confirm which facility molds your part number before you approve the tool. Our Protolabs alternatives and Xometry alternatives pages compare both with other routes.
Apple Rubber and Robinson Rubber: seals and custom compounds
Apple Rubber in Lancaster, New York is the only molder in the group that publishes a minimum order, and it counts in dollars: $100 per line item for anything in stock and $1,000 per item if the part has to be manufactured. It is also the only one that names ASTM D2000, in an engineering article explaining the line call-out, and it states AS9100D, ISO 9001 and ITAR. Robinson Rubber Products in Minneapolis has been molding since 1938, states ISO 9001:2015 and more than 1,500 formulations, and runs LSR, overmolding and insert molding. Neither publishes a lead time.
Which one to call first
Match the molder to the stage you are at. For a prototype you need in days, start with Konark or Rubber Industries, the two that publish both a tool price and a turn time. For a medical part, start with Extreme Molding or SIMTEC. For automotive, SIMTEC. For a silicone gasket at moderate volume, Stockwell. For a quick online quote on a simple LSR part, Protolabs. Then send every shortlisted molder the same drawing with the ARPM tolerance class, the material or ASTM D2000 call-out, and quantities for prototype, first production and annual volume, because that is the only way the quotes will compare.
Plan around the stages rather than a single date. A silicone part arrives in three steps, tool, first article and production, and an assembly line waiting on it should be scheduled against each one. If you are building the rest of the product in house, production scheduling software lets you load the molder's tool and first article dates into the plan so a late mold moves the assembly dates with it instead of surprising the floor.
Shortlist the right silicone molder in one brief
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Frequently asked questions
Which US silicone manufacturers make custom molded parts?
Molders such as SIMTEC Silicone Parts in Florida, Extreme Molding in New York, Konark Silicone Technologies in California, Stockwell Elastomerics in Pennsylvania and Rubber Industries in Minnesota make custom silicone parts to your drawing. Dow, Momentive and Wacker make silicone material, not finished parts.
How much does a silicone injection mold cost?
Published starting prices for simple tools run from about $850 to $1,500. Rubber Industries states steel prototype molds from $850, Konark states tools from $1,295 and Protolabs states injection molds from $1,495. Multi-cavity steel production tools for LSR cost more, and molders price those from the drawing.
Do US silicone molders have a minimum order?
Most do not publish one. Apple Rubber is the only molder we read that does: $1,000 per manufactured item and $100 per line item from stock. Protolabs states it works without MOQs. The practical minimum is the tooling cost you pay before the first part.
Which silicone molder is fastest for prototypes?
Konark publishes 1 to 1,000 silicone prototypes within 3 business days, Rubber Industries publishes prototype steel tooling in 5 to 15 days, and Protolabs publishes LSR parts in 15 days or less. Speed depends on part complexity and whether a stock compound is acceptable.
Which US silicone molders are ISO 13485 certified?
Among the molders we read, SIMTEC Silicone Parts, Extreme Molding, Protolabs and Xometry state ISO 13485 certification. Extreme Molding also states FDA registration, and SIMTEC runs Class 8 clean room molding. Verify the certificate and its scope directly before you place a medical order.
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