I started with an old trailer that was given to me by a "friend". First mistake
Disclaimer: I am not an engineer or pretend to be one. This is just guide of the method that I used to build my trailer. Please check your local laws before attempting to build your own. I was a pipefitter all my life and did quite a bit of welding. Do not attempt to weld your own trailer unless your qualified to do so. By all means please work carefully and use all the necessary safety equipment required. After 60+ plus years I can still count to 10 on my fingers! Can You?
As I took possession of my new trailer I knew I would have some work cut out for me. The crossmembers were in good shape, new 13" tires, new bearings and hubs. The problem was the side rails were very rusty, the trailer was too narrow for my paddles to fit between the tires. If I was to use this trailer a lot of work would be required to put it in useable condition.
I decided that it might be better to just "bite the bullet" and go and buy a new one. After much research and looking at many trailers I found problems with all of them. My paddles are 83 inches to the outside edges and most trailers are have 82 to 84 inches between the fenders. A couple that were 86 inches had drawbacks in the axle area for mounting it forward enough to give me a reasonable tongue weight. The main drawback was the $$$$. I really didn't want to spend close to 3 grand just to get to the lake with my new toy. It was then I decided to take another look at that rusty old hunk that was in my yard,