The base
The sides I cut with a jig saw. I traced them out with a string till it looked right.
The bottom has rubber glued to it.
1/8" plywood glued and screwed to the 3/4" side plywood.
headliner glued for the inside.
shelf and back wall installed
bending the roof with headliner on

started the trailer with a 2100 lbs torsion axle
finished trailer with primer
trailer with paint
metal on, I cut most of it with a double cutter
Rubber glued up the sides, primed so ice and water shield sealed to it.
I have more but that is enough for now.