I used a couple of step ladders and angle iron to hold the base above the scooter so I could get measurements for the supporting parts that connected to the scooter.

I made four brackets out of 11 gauge steel, .120 thick.

I needed a radius for my little brackets to bolt to the scooter. This old 3M wheel is the same size as the back tubing on the scooter.

A couple of brackets. I laid them on the scooter tubing and drilled them out.

This isn't a good picture of the bracket. What I did was put it length-wise in the vise with only about 1/4" of it sticking in the vise, then I hammered it, then put a little more in the vise and hammered it some more until I had a half moon in it.