Arc/Mig/Tig Welder: That thing that makes metal hot and results in setting adjacent things on fire. Also used for providing that extra burst of light your eyes have been craving for so long. Occasionally sticks pieces of metal to one another-usually the wrong ones. Also heat warps any project into a twisted unusable lump or blows so many holes in it that it resembles(melted) swiss cheese. When it finally gets set up properly to complete any job it immediately stops working.

Gas welder: Same as above but slower. Also never has any gas when you need it.

Reciprocating saw: Used to inadvertently puncture any and all soft lines located anywhere near the place you're actually trying to cut. Also used a practice device for blade replacement.

Miter saw: Cuts perfectly straight lines 1-5 degrees off from where you set it. Never the same cut twice.

Impact wrench: Designed to test patience and sanity by overtightening lug nuts to the point where the stud spins freely in the wheel and the lugnut is permanently stuck to it. Wheel removal=impossible. Only happens on Friday or Saturday nights for a guaranteed wasted weekend.

Paint sprayer: Originally designed to apply paint to automotive surfaces, but excels at applying paint and fun surprises to your intended surface such as dust, twigs, leaves, insect parts, oil/water bubbles, and the occasional small bird. Paint sprayers all share a unique feature as well: they change the color of the paint you bought to in no way resemble what you looked at in the store/catalog/etc.

Airless paint sprayer: Does the same thing but for houses.