Imitation is the sincerest form of flattery? I really liked the fold up/down version and I liked the filtered version, so I combined them. Here are some photos of in-progress construction. I'm waiting for the vent hose and blowers to arrive and need better nails for the hardboard backer before I put that on.
The dimensions take advantage of precut 2'x4' hardboard pieces although with a jigsaw the stuff cuts pretty easy and I could have just drug a big board home. The width of the front and top is 48" less a little bit so that the front overlaps the board on the sides. The side boards will overlap the back a bit. I had to trim board for the two folding sides and the fixed sides. No biggie.
In the bottom the tray is for 2 pairs of the cheap 20x20 filters; 2 on a side. The suction will be installed under that; I'm thinking of just using some rod made from wire hanger material to make a cross that retains the 4" dryer vent hose in a hole that matches. That goes to a couple of bilge blowers run off of a AC charger, and then out the window.
This thing is really light and easy to move around. I can move it outside if I want, or maybe even paint in the storeroom so I don't' heat up the shop when the AC is on.
The last picture shows how the sides fold under the top. I had to make the back 3/4" higher than the front to make that possible. The top hinges are on the back not the inside so when open the top sits up a bit from the back rail - but that's no big deal because the hardboard backing extends down and covers the gap no problem. And there is air sucking in anyway.
The furring strips are warped a bit even though I got the best they had. They work out fine if you decide its okay - its not furniture.
I still have to figure out how to attach the chicken wire. Probably will screw some supports to stick out from the bottom railings, or better just make two long pieces to go from one side to the other under the front and back.
The blowers are $35 a piece on amazon and 50' of exhaust hose $15. The wood, hinges and strips here cost another $50 or so. I had glue, tools and screws. Not overly expensive for making painting inside palatable!