Is there a qicker way, like an autoLISP or command I'm missing, to create a polyline around other polylines, rather than draw around all of them manually? I want to keep the original polylines, but also to trace essentially a boundary around all of them for plotting purposes.
I don't quite understand what you want...If you want to essentially create a copy of the polyline so you have two in the same spot, I would select the polylines, copy with basepoint 0,0, paste with basepoint 0,0. If you want like a border or boundary with the same shape, you could use the offset command.
I don't want a copy, though. I only want the new polyline to "copy" (Best adjective, I guess) the exterior of all the other polyline shapes. I don't want the new polyline to have any of the other, interior parts. Just a border.
If you can enclose the object(s) within another object, you can use the BOUNDARY command. Your object(s) will be the "island"
Not quite as efficient as ShrinkWrap.lsp, but same result.