So I decided to build my own flowhood after seeing several builds. I completed the first step today by acquiring the HEPA filter. I will update this thread as I progress so you all can see exactly how I build the flowhood and why I decide to do things the way I do. Hopefully someone else can benefit from this build, and hopefully others can offer my advice as I build it!
So, step one was acquiring the HEPA. I managed to find locally a 24" x 12" x 6" - 99.99% Efficiency @ 0.3 micron, and aluminum housing with rubber gasket.
Next, of course is to find the right blower to match to the filter.
Then, the build of the frame. I've got access to a large supply of wood of all sorts of sizes. So hopefully I'll be able to find some good pieces.
Wish me luck!