I came across a great idea for a traveling Lego box on line but wanted to adapt it to be a bit more 3 year old friendly (their box looked hard to open) and....quiet :) Here's what I came up with.
DIY (Quiet) Traveling Lego Box
What You'll Need
Wood box (with latch) I found mine at Michaels
1 Square of felt
1-2 Lego Baseplates
Paint the wooden box the color of your choice
After the box is dry, hot glue Lego baseplates to the top of the box
Cut a piece of felt to fit in the bottom of the box then hot glue it to the bottom
Fill with Legos
Houston (3) loves his new Lego box! His little creations stick to the baseplate, though he can still open the lid and look for pieces.
My favorite part though is that the felt on the bottom helps keep the Legos from clattering around.