Sure i may be able to take pictures later but expect to be pretty busy this week.
But construction is pretty simple, it's just some hvac joist panning tin cut and then bent to form a square with about 1cm of overlap on one corner and is just aluminum taped together along that overlap as then i can refill the filter as needed later. But it made just big enough to slip over my fan, and is held in place with a magnet thats glued into the roof of the cabinet.
It has about a 0.5cm lip on the front side that was folder over to hold the expanded mesh in which just acts as support, be behind that there is some thin filter material "actually carbon air filter material used for home air purifiers" its a bonus but i only used it cause i had some on had otherwise i would of used whatever i had available. But behind that then ther is my layer of aquarium carbon which is 3-4cm thick, followed but another cut out of the filter materials then the expanded mesh and its just taped in place with some aluminum tape.
I use to run a thicker carbon bed in previous builds, but this last round maybe due to the fresh carbon and lower smell plants i had zero smell, but i think a bit quicker airflow throw the filter has contributed to the scrubbing as possibly i was running too low.
If i was running really stinky plants the filter typically would be overpowered in the last couple of weeks of flower, but a standard electrostatic house air purifier would typically take care of any extra smell.
I have planned to add a super small ozone gen to my exhaust air that would say run 30sec-1min every hr during peak flower if needed but have yet to implement that, and haven't needed to yet either.
Pictures are easier but i'll grab some next time i can and tag you in them.