No carpentry skill or excessive tools required.
I built mine from a clear pine 6' 1"x10" board, rippppppped into 1x1.5 on the table saw, but you can just buy them that size, or use any size. after the ripping, I had a full piece (6x1x1.5) and a half piece left over - using under 1 board.
I think you'll be able to see the instructions fairly well from just looking. essentially, it is 36" long, 16" deep, and 28" high.
Nail the height+depth boards into an L shape, nail the bottom two pieces that the bass rests on about 16" apart, nail the top piece. the diagonal supports aren't entirely necessary, but I cut a 45 degree angle on either side of the support, and nailed it flush. you can make them go higher with longer boards. (I am captain obvious).
drill the holes in the top piece, glue the dowels into the holes tightly. I cut the dowels 3.5 inch long, and drilled my holes 1/2 inches into the top board, but that can vary depending on what size necks you play.
this design will hold 6-7 electric basses, depending on thickness. it's really quite simple.

just a sample of my basses, and a couple guitars.
still haven't figured on how to store my mandolins, yet.

pushed the fretless jazz neck off the bar to show.
at this point, I hadn't wrapped the top bar in the same black cloth as the bottom. it isn't manditory, but I suggest you do it just incase the thing gets hit, and the wood could damage the neck. that having been said, I sanded ALL corners heavily and round, so it should be fine.

your going to have to elevate the bass, because where the body fits down between the two pieces, if it's flat on the floor the body will just actually be on the floor

quite simple, really.
this one needs to be elevated a bit more, just for vanity sake, but that'll come later.