Crown-molding support acts as an extra set of hands
Holding up crown molding by yourself while nailing it in place can be a real balancing act. A quick trip to the home center produced all the parts I needed to build a support for the task: a 10'-long 1×2, a pair of flathead machine screws, washers, and corresponding wing nuts. I had a couple tennis balls already, but you may need to purchase a tube of those.
Saw the 1×2 into 5' lengths and cut a 16"-long, 1⁄4 "-wide slot in one end of both halves. Drill a 1⁄4 " hole above both slots for the machine screws and assemble as shown. A tennis ball skewered on each end of the support prevents it from marring the molding or slipping off when in use.
—Oneil Long, Mound City, Mo.