Many thanks everyone. Having trouble finding a pleated HEPA filter that will fit my design (which is strongly based on the YouTube vid I linked to in my OP)
The actual pics below are from the YouTube vid.
My base/ bottom box will look almost identical as per his pic here
The top box with the filter media sits in the bottom box like this
He’s used off the shelf carbon filters like this
I’m using something like the pic in my OP, probably 8” / 200 mm in diameter, with mesh at the bottom so I can fill with my own loose carbon
Here’s a not at all to scale drawing of the top box
So I’m going to have 8” / 200mm diameter filters and the maximum height of the box is 6 1/4” / 160mm
It will have a lid on it something like this
So in reality I need a round pleated HEPA filter just over 8” / 200mm in diameter but no higher than 6” / 150mm
I’ve found these, do people think they will be any good? I’ll need to block the tops off so all air is pulled through them.
https://www.amazon.co.uk/SPARES2GO-Hepa-Filter-Dyson-Purifier/dp/B07H2XDDZP/ref=asc_df_B07H2XDDZP/?The whole point of building my own fume extractor is because to me, around £500 for a half decent one is too expensive for what it is.
So far I’ve spent £15 on the 2 boxes, around £20 on hoses and grill, £50 on fan and around £10 on other bits like sealant.
That comes to £95 and all I need to buy apart from filter media are the 8” / 200mm round inserts as per my original post. Can’t see them costing more than £20 for the pair, so £115 plus filter media.
Ordered 2.5kg activated carbon for £16.50, if those HEPA filters are suitable then another £39
A bit better than around £500 plus for a decent one, that’s presuming it works just as well
I don’t solder all the time but have health issues with lungs hence don’t want to inhale any fumes