A scissor jack is the type of jack most familiarly used with cars. It takes the form of an "X," which in operation looks most like a pair of scissors. Alternatively, it takes the shape of a diamond and retracts to almost flat like many tire replacement jacks. In either case, scissor jacks are very compact when closed and very extended when open. Since scissor jacks consist of a pivot and a rotating threaded rod, a small hobby scissor jack can be quite easily made for smaller weight jobs like model building and instrument repair.
Cut two pieces of 1/2-inch plastic with a hacksaw or jigsaw. One piece should be approximately 1 1/2-inches square. The second piece, for the base, cut to 1 1/2 inches wide by 2 1/2 inches long.
Cut eight support legs of equal length from 1/4-inch plastic using a hacksaw. Cut these pieces 1/2 inch wide and 2 inches long.
Drill quarter-inch holes in the center of each of the eight support arms using a power drill. Drill the holes 3/8-inch in from each end of each plastic piece.
Cut a threaded 1/8-inch rod to a length of 3 inches with a hacksaw.
Cut two 1/2-inch lengths of 1/4-inch outer diameter PVC pipe with a hacksaw. Drill 1/8-inch holes through the center of each piece using a drill with a 1/8-inch drill bit, then use a threading bit to create a threaded hole in one of the pieces. Do not thread the other PVC piece.
Connect the plastic arm pieces to the PVC sections, one at each end of the pipe segment. Use a self-tapping screw large enough to hole the pipe. Connect two plastic legs to each piece, making sure they can still swivel freely.
Attach these assembled jack sections to the base and the top, respectively using machine screws, small washer and nuts. Tighten each screw in the top and base securely using a socket wrench.
Insert the threaded rod through the center of the the PVC side segments.
Attach a threaded handle to the threaded rod, turn the handle a few times to secure it to the rod, then rotate the threaded rod to raise and lower the mini jack.
Do not use thin material for the support arms as they can bend and fail.