DIY Air Purifier for Laser Cutter

I believe that a laser cutter is the most versatile tool for a high school makerspace. For an idea of some of the projects done in Project Make over the last two years, see this video.

Exhaust from laser cutters contains smoke and fumes that range from annoying to hazardous depending on the material being cut.  Sending the exhaust outside is the most common approach, sorry neighbors!

I will be taking the slick new Full Spectrum 5th generation laser on the road to a couple of upcoming events at which ducting to the outside will not be possible.   Commercial air purifiers costing upwards of a couple thousand dollars are a bit out of my price range.

There are a few designs for DIY versions floating around the internet, here's my first attempt at building one on a budget:

Starting with a small metal barrel for the enclosure ($10 at a local salvage yard),

I cut the bottom in a none too elegant fashion using a drill and jigsaw and made a 2x2 support to hold the internal weight and raise the bottom to allow the air to escape.  Not pictured is a piece of 1/4' hardware cloth covering the hole.

Aluminum screen stapled to two rings cut from 3/8" plywood, held about 6" apart with some 1/4" bolts served to contain about 20 lbs of activated charcoal (available on ebay for about $60) that was put in first.

 A HEPA filter, and other assorted HVAC filters from Home Depot ($25 for the three pictured - I could have probably cut the cost in half by skipping the odor absorber) were cut to layer inside the can.

I had a quiet inline fan that moves about 250 cfm laying around which I placed in a hole cut in the lid.  Similar fans are available for around $100.  I still need to secure the fan to the lid and seal the seam a little better with caulking and or tape before I try to cut acrylic, but the first run told me that it will work just fine for my immediate needs cutting cardboard goodies!

Now, where to spend all the money I saved?????