Wood Shop Projects
Here's a great You Tube video by Jim Halbert of jimswoodworkingshop . He shows how to constructing two different blast gates; one powered with a drill motor and the other with a solenoid. According to the video you can build either of the blast gates for less than $75.
In the first example Jim uses a Harbor Freight Cordless Drill for an actuator and the second example he uses an electric solenoid. The construction of automatic blast gates is a bit of a specialised project, however for the larger shop with lots of machines automatic blast gates are essential parts of dust collection.