Escapee bunnies - Wire Cube System cage

We brought home two Holland Lop 8 week old bunnies a week ago and they sure do want to escape their cage area. I used the Wire Cube System to build a cage that is 124" by 42". they are small bunnies, the one is just a little bigger than my hand. the one jumped up and hung on to the side of the cage, about a foot and a half off the ground. I'm afraid she's going to do that when we're not around and fall and hurt herself. Does anyone else have a cage similar to mine and have the issue of their bunny trying to climb out? Any advice?

The picture I attached is the cage before I added another few feet to the right hand side of it and I have cardboard around the bottom level of the cage attached with zip ties.

Adding a roof is really going to be the main deterrent. Bunnies can be very stubborn and single-minded. You could use more cubes to make the roof, or some people just drape a sheet over the top and peg it down.

Put something as a roof so he can't jump or climb out