Cardboard Truck: Seat Cushion

I'm going to break this down into several posts highlighting the different components. Along the way, I'll offer alternate options and advice based on my own mistakes experiences. If you are looking for the perfect tutorial on making a cardboard vehicle, this might not be for you. However, if you are looking for ideas, inspiration, and enough help that you (yes, even those of you who doubt your crafting abilities!) can make something the kid in your life will love, keep reading!

Several weeks ago I went ahead and made a seat cushion for the truck. I'm a believer in using whatever you have and what I had was bubble wrap. We have plenty of it from moving breakables across the world on a shipping container and it makes a nice cushion when piled up. Before I give you the details of how I made it, I'd like to offer a few suggestions for those who might not have such a huge supply of bubble wrap and don't want to buy any. Several other options for a seat come to mind:
a sturdy shoe box (or box about that size)
a piece of thick foam from a fabric/craft store
a small pillow
just leave it out- If you cut the windshield low enough, just let the kid sit on the floor of the box. He won't mind.

Ok, here is how I made my bubble wrap seat:
1- Stack up enough bubble wrap to be as thick as you want the seat. Mine measures about four and three quarters.
2- Wrap tape around all layers of bubble wrap starting with a piece around the center. Then do tape strips close to the edges. You can use any sort of sturdy tape you have: Duck Tape, Masking Tape, Box Tape. Scotch may not be strong enough.

 I added a piece of thin foam that I had on top, but it's not really necessary.

3- Cut a piece of fabric big enough that it will cover the top and sides of the bubble wrap and wrap around to the bottom where it will be secured.
4- There is no exact science to how I covered the bubble wrap with fabric. I used a hot glue gun and stretched and folded the fabric as I worked my way around.
When I got out the box last week and started put the whole thing together I realized that my seat stuck out a bit too far. It was easy enough to alter. I ripped the fabric back off and used a knife to slice through the bubble wrap. Then I re-taped the edge I had cut and recovered it with fabric. Initially the cushion measured twelve by twelve. I cut it down to twelve by eight and a half.

Here is a picture of the final product.

The bottom

 And the top.

Any other thoughts on what might make a good seat cushion?