The link below will take you to a step by step image gallery of my mini camping/storage trailer build. I'm towing this with my 2012 Mazda5. I started with a harbor freight frame measuring 40-1/2" x 48". It has 12" wheels and is rated for 1100 lbs. This is a good fit for the Mazda5 which has about 1300 lbs cargo/towing capability, based on the difference between curb weight and GVWR. I've taken the trailer out a couple times so far this spring, lightly loaded, and it pulls very nicely. Now I'm even more excited for camping season.
http://imgur.com/gallery/eNzXM/new
http://imgur.com/gallery/eNzXM/new