My son has always loved playing with Legos so it didn't take much to convince him to allow me to convert one of his old Lego containers into a lunchbox.
I needed closed cell foam to act as insulation and I found a 1/4 x 20 x 15 sheet ($6.25) of it at my local outdoor gear shop. I was able to cut six pieces out of this one piece of foam.
Originally I thought of gluing the foam into the container but quickly decided that would turn into a mess when it was time to wash it. I ended up sewing a sleeve to hold the four side panels and the bottom panel.
I used waterproof nylon (not "ripstop" as stated in the video) to sew the sleeve. The original size of the nylon was 18.5 x 26 inches. I sewed the sleeve so that I could remove all the foam and wash the sleeve. The sleeve fits snugly inside the Lego container.
The lunchbox handle is made from one inch wide flat nylon webbing and is attached to the Lego box using a pop rivet tool. I have a feeling this attachment point may fail quickly but we'll see.
I've included a video and extra photos (below) if you're interested in more details.
Creating the Lego Lunchbox...
Here's what the Lego box looked like before I started.
Closed cell foam sheet measuring 1/4 x 20 x 15 was able to supply all the material I needed for the insulation. You'll notice the four side panels have a keystone shape - - they are 8.25 inches tall and 6 inches wide at the top and 5.5 inches wide at the bottom. The small square is the bottom and the large square is the top (just under the lid).
I needed to leave gaps in the insulation to allow for the folding fabric sleeve.
Sewing the sleeve.
Completed sleeve which hold the insulation panels. Notice bottom flap is sewn to one side panel. All foam pieces can be removed so the sleeve can be washed easily.
The handle is one inch wide flat nylon webbing. I attached the webbing to the box using a pop rivet tool.
This view is the under side of the box and shows a flat aluminum bar intended to reinforce the attachment point of the lunchbox strap.
Check out this cool contraption my brother-in-law created. It helps keep Lego pieces from going everywhere. Super useful. My son loves this thing. Collectigo.com