Not sure I'm understanding the question.
Are you asking about this thing slid into the 2" receiver:
Or this unit bolted to the trailer tongue that includes the 2" receiver tube:
I made the ball coupler (top picture) that slides into the 2" receiver hitch thingy. Was simple with 2" square tubing and a 1 7/8" ball coupler.
If the second picture, I made that too using a section of 2" receiver tubing and a larger piece of square tubing I attached the receiver tubing to (welded and bolted together when attached to the trailer's tongue).
I'm not using it (second picture and one below) anymore (I changed the tongue of my trailer to a straighter design). If you want it, you can have it (PM me). It slides over a square tongue measuring 2.5" x 2.5", and extends your trailer's tongue a bit. I just went out to the shop to see if I still had it and took a picture. Yup, just a bit dirty. It bolts on the tongue from the sides and the top.
New straight design/extended tongue on the trailer: