[londons_explore]

Looks to me like a low cost version of the same could be designed with 2 CPU fans ($1), and a large 3D print ($1 - for the DIY version) or injection moulding for a commercial version ($0.30). Do time-sync between the units with grid frequency sampling (free), and have the whole thing controlled by a 2 cent microcontroller and a pair of triacs.

The whole thing, designed and made in China could probably come to a BOM under $4, and retail in the USA for $12.

[4gotunameagain]

While I agree with your points, $0.30 for injection moulding would need quite the scale, and I have doubts about whether two CPU fans would have enough power to flow enough air even in the absence of a HEPA filter.

[londons_explore]

Injection moulding is cheaper than you imagine now. The cheapest moulds start from about $250, and there are plenty of companies who will make a mould and make and ship 5k parts within 7 days.

These designs would need quite a few changes to be injection moulding compatible - for one thing the fins are probably going to have to be flat not circular due to draft angle requirements.

Changing the core to a roll of embossed steel foil might be a better bet, and whilst that would add about $1 to the price, it would also make the product work better and be more compact or more efficient due to a higher thermal mass in the core.

[4gotunameagain]

Got any links for the $250 moulds and companies ?

Maybe I could use them in my own project :)

[londons_explore]

Send these guys a message:

https://zhongshengmould.en.alibaba.com/

Never pay for a mould to be made with plans to ship the mould itself to another manufacturer - it's a common scam. Always make mould+make parts as a single transaction.

[4gotunameagain]

thanks !