I built this DIY air filter from these plans –
Here is a picture of the one I made.
I received my official Glowforge air filter and no longer need this one. It seems to work fine, but I have no way of telling for sure. All I can say is that it worked fine for me. This would be a “use at your own risk” kind of thing. It has received a relatively light amount of use and I have the rest of the bag of unused activated charcoal. I am happy to give this to anyone who wants it. I live in Eugene, Oregon, and you would need to pick it. I’ll hold on to it for a few days before I dismantle it.