I'd suggest thinking out of the box a bit more, rather than building yet another robot arm.
3-axis arm suspended from an overhead crane suspended from the rafters? Giant
wire bender that can make arbitrary structural shapes out of rebar? Construction robot with a nailgun and circular saw that can build tiny houses out of plywood and a pile of 2x4's? Hybrid 6-axis CNC that can do both subtractive and additive manufacturing?
Robot to lay down carbon fiber epoxy in
arbitrary shapes? Research platform for soft/compliant robotics for strong but safe human-robot interaction (see
1,
2,
3,
4)?