The project was a welding corner that would include an exhaust fan. The building was finished about a year ago and the back wall had only drywall with white latex on it. If you notice there are two power boxes. I wanted three phase power which takes three breakers for each three phase use. This means I had to add another sub-panel to accomodate my shop items. This is the smaller box on the right.I had picked up a 12" Dayton fan (see Pix) on ebay for $150. I changed the motor to a 3/4 hp 3 phase motor so I could use a variable speed drive to control the fan speed. I picked up all of the items on ebay.I found the hood that goes from a rectangle to the 12" round size at a business that was closing down for $5.00. Then I purchased a 12" standard HVAC ducting elbow and a 12" round to rectangular duct piece. I connect that to an outside shutter from WW Grainger, mounted the fan with 4 rubber mounts and connected the components together. Fortunately everything went into place.I had a local sheet metal shop shear the shroud pieces out of 18 gauge metal to size, handling modifications necessary with my metal cutting band saw or my sabre saw. I then wired the fan through the variable speed controller using 1/2" & 3/4" conduit. Finally, all assembled I sprayed on a heavy coat of primer and then fire-engine red enamel.I also built the welding bench from metal tubing and 3/8" sheet metal.