I got ya covered.

1. Buy some rolls of plastic bug screen material and cut it to 20 foot lengths and make 10 foot long "loops" out of those lengths of bug screen material. Maybe sew the ends together with laminated fine copper wire for winding electric motors or by first stapling and then using a construction adhesive to glue both ends to a line marked down the middle of a 1X4 board.

2. Buy eight long pieces of 1 1/2 inch ABS plumbing drain pipe and eight 1 1/2 inch ABS elbows. Make two frames, both square. Use 2 X 1 1/2 Fernco couplings at the corners instead of glueing the pipes into the elbows. That way, you can quickly and easily dismantle the frames for easy transport. (I don't know what standard lengths ABS pipe comes in, or how much space you need around the chop saw.)

3. Slip your PVC pipes into the bugscreen loops and connect the corners so that you have two square frames made of pipe connected with loops of bug screen material.

4. Connect 4 light duty chains of equal length to the 4 corners of the top frame, and have those chains attach to a central loop or hook.

5. Have someone help you lift up that assembly and set it around your chop saw.

6. Now, use an inexpensive electric hoist to pull the 4 chains up, thereby raising the top frame by the 4 chains attached to it's corners. As the top frame rises, it'll eventually pull the loops of bug screen taught, and begin to lift the bottom frame off the ground. That's when you want to stop the hoist from lifting the top frame any higher.

7. Do your cutting, and then lower the top frame to the ground and step over it to get in and out of the dust enclosure.

Alternatively, you can do something more elaborate:

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