Got started on my first build, initially was going to have the chassis built by a local trailer builder but they did not use torsion axles and I ran across a deal on a welder when buying a generator from someone so I decided to do it myself. My steel order got mixed up, was going to be a 1/8" 2x2 tube frame, some of my tubes were 3/16ths instead of 1/8 so I used them for the perimeter of the 5' x 10' frame and the 1/8 for the cross members. Went with a 2.5 x 2.5 tongue which went back to the first cross member and extended 60" past the front of the frame, 3/16 angle supports for the tongue. Flexride 2K torsion alxe, I did not order off the internet but called SouthWest Wheel in Texas. They have two locations there, I called the main number to ask questions and they gave me the number for the office where the axles are actually put together. If you order one you need to know not just the outside frame to frame measurement but have to consider what hubface to hubface measurement will allow the pivot arms to clear your trailer body should your body extend past the frame as mine will.
Just have to add the trailer Jacks and tongue jack and the chassis is done.