We have an indoor bouncy house for our daughter. It's great fun, especially when other kids come to play. Plus, it literally pays for itself in babysitting fees because several couples can enjoy dinner and talk about boring adult stuff while the kids entertain themselves in the bouncy house (and then immediately fall asleep exhausted at the end of the evening).
Our specific model is a Island Hopper Jump-A-Lot Double Slide Bounce House 2012 available from Amazon here. I've been very happy with it, except that the walls along the top slide aren't high enough, and I fear someone running down the slide (as 3-year-olds are wont to do) might fall out. To help prevent this, I sewed on webbing loops and installed a rope safety net, effectively extending the wall upwards.
Step 1: Planning the Net
Here, I'm assessing the situation and planning the placement of the net. I neglected to take pictures before sewing on the webbing loops, but the images still show the problem clearly.
Corvidae hasn't fallen out. However, in the first image, she's standing on the tips of her toes and you can see how close she is to going over. The second and third images are more relaxed postions.
Step 2: Sew on Loops
After deciding on the placement of the loops, I pinched the bouncy house's wall material and sewed on webbing loops. The loops are folded over, and the stitches go through a sandwich of webbing and bouncy house nylon.
Step 3: Loops While Inflated
Here are the loops with the house inflated. Very little air leaks at the loops' seams.
Step 4: Lace Net
Here I've laced some nylon rope through the loops and tied it tight. The net slightly deforms the bouncy house, primarily pulling the blue corner tower towards the slide, but it doesn't really affect bouncing performance. I leave the rope laced when I deflate the house, and it equalizes when re-inflated.
The ideal solution would be to sew on more wall material to actually raise the inflated wall. I was concerned I would never actually accomplish this perfect solution before someone fell out, so quickly installed the net. The net might look like it could strangle a child, but the kids aren't totally put out to pasture in the bouncy house -- someone is always paying attention. Untangling a child from the net is something you can walk up and fix while you can't do same after someone falls onto their head.