Fume extractor for 120mm computer fans and 130mm charcoal filter.
Use M4 screws for mounting on underside of rail. Wood screws will suffice for attaching the fan and filter. I had to drill out the holes on fan mount for the screws i had laying around to fit.
the holes can also be drilled and threaded for bolts.
Edit 20jan19 - Added some photos of my finished project of solder/grinding protection setup. Two fans with carbon filters, led strip and adjustable plexi glass protection screen.