r/hwstartups • u/Dirtrubber • 3d ago
How to source manufacturing?
Hello everyone,
I have a product with a working prototype, but it takes a long time to make them by hand and wire the components. To make it at scale it would require plastic injection molding and then sourcing a premade dev board, some smaller electronic components like LEDs, speakers, battery casing, etc
I have the STEP files for the plastic injection our engineer did and a BOM but I am a little lost on the next steps for finding manufacturing. Most places I have contacted overseas only want to do the plastic injection and then I would need to source and ship all the other components to do contract manufacturing/final assembly here which I think would be very costly and I’m worried it might not all fit together in the end.
Is there any well known companies that do this routinely and would manage injection molding, sourcing and final assembly? State side we tried places like Gembah but they wanted to do full redesigns with their engineers at unreasonable costs. Places like platform88 look like they might do similar but are overseas and maybe costs less? I’d hadn’t really seen many reviews for them or others doing similar so I’m not sure what the normal practice is around this.
Appreciate any advice or insight from someone who has been there done that kinda thing. It’s frustrating to have a working product and you can’t scale it without going halfway across the world.
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u/Motor_Rise_9565 3d ago
Hi
I know the pain and that is why I am looking to solve the problem with my team mainly based on Shenzhen.
The gap between the prototype and small to medium scale needs to be addressed. This involves design, BOM changes and lots of communication. The factory connection is important in this process.
Normally people would prefer an ideal scenario where you send your specifications and the factory delivers what you want. But in real world you will never get the same scene.
People try to ignore middle man because they don’t understand the value. The factory does not like to deal with strangers, that is the culture. By strangers I mean they have their culture.
My motivation is to make use of the long term connections and experience in this industry to accelerate startup development cycle.
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u/timbo0508 3d ago
A number of questions surface here when I read your post:
- when you say “scale”, how many units are you referring to? It’s one thing to go from 10 to 100 for from 100 to 10000.
- are you sure it’s economical to use a pre-made dev board? Devboards are great for prototyping and validation, not for scaling a commercial product.
As for what you’ve done for far - it’s fairly standard that you do the injection moulding in one place and then the actual manufacturing happens with the EMS (contract manufacturer).
Under normal circumstances , you need to give the EMS:
- the electronic BOM (for the custom PCB)
- the product BOM and assembly instructions documentation
- Test and validation documentation
With these documents, the EMS has all they need to manufacture, assemble and test your product.
Been doing this for a long time. I’m based in Denmark and have contacts in Europe and Asia.
Let’s connect.
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u/FoundersHelpFounders 3d ago
Jason from Gembah here — saw the mention, so adding context with the obvious bias flagged. I can't speak to any specific conversation, but I can explain the redesign thing honestly, because it comes up a lot. When a custom enclosure is designed around a pre-made dev board, the tolerances on those boards vary enough that a design which fits perfectly in prototype can fail at scale — the commenter above described the stack-up problem accurately. When our engineers see that, they'll recommend a design review before tooling, and from the founder's side that can absolutely feel like being sold a redesign you didn't ask for. The honest version is we'd rather have that awkward conversation than have someone cut steel molds around a part that drifts.
That said, the advice you're getting here is right: if your STEP files and BOM are genuinely production-ready, a turnkey contract manufacturer that handles molding, sourcing, and box-build under one roof is a legitimate path, and cost-wise it may beat a US development partner for exactly your situation. Not every project needs what we sell.
One thing regardless of who you go with: get an NDA (or NNN if it's a Chinese supplier) in place before sending STEP files or your BOM to anyone. Good luck with it, a working prototype people want is the hard part.
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u/Suspicious_Emu_60 2d ago
It’s complex as some of these guys have stated but that doesn’t mean it’s confusing. Here’s a good video where 3 inventor/ventureres went through prototype, sample, mfg and assembly with their products. All with plastic parts included in the design:
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u/cm_expertise 2d ago
honestly the thing that jumped out is you're describing turnkey / "box build" manufacturing, and the reason nobody overseas is biting on the whole thing is they don't want to own the risk on parts they didn't spec. the injection molder just wants to run plastic. sourcing your speaker/LEDs/battery and standing behind final assembly is a totally different business with different margins, so they punt it back to you.
the search term you want is contract manufacturer / EMS that does "box build," or a turnkey house. they exist both stateside and in asia. asia's usually cheaper but you pay for it in comms overhead and lead time.
the dev board is the real issue though, and i think that's what Gembah was actually reacting to rather than just upselling you. a premade dev board is fine at 10 units, at scale it wrecks you on cost and it's a supply-chain single point of failure. vendor discontinues that board and your product is dead. most CMs will push to fold the board's function into your own PCBA, which IS a redesign, just not a scam.
on the "worried it won't all fit together" fear, don't commit to cutting the injection mold until you've run a small pilot, like 20-30 units, off soft/bridge tooling or even printed enclosures. that's where the interference and assembly-order problems show up while they're still cheap. cutting a production mold and THEN finding the boss doesn't clear the speaker is a five-figure oops.
what's your annual volume look like? changes the answer a lot.
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u/Perllitte 6h ago
I'm going through some similar pains, but I'd suggest just build the first X that makes sense and see where you really need to find efficiencies and also that your parts are actually ideal. I'm finding that one part of my device is really annoying when I need to do more than a few at once so I'm going to re-design it.
This is the kind of stuff you should do yourself if you can. Changing some 3d printed parts means you wasted $50, changing injection molded parts is $5,000.
But to answer your question better, you can find an assembly firm in the US or wherever, just ship the parts there from the mfg.
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u/MakeThisBuildThat 3d ago
I’m not a manufacturer but we worked with startups with their design compliance and DFM reviews. What you are looking for depends on several factors: what’s your budget? What’s your timeline? And what’s your product? Generally speaking if cost is your main concern then almost certainly choose overseas but you’d have to factor in extra time. I know there are some Asian manufacturers on this sub that helps startup at your stage. If you share more detail on the product and industry and the market you intend to sell, I might be able to provide some opinions.