Trailer it's made from two steel profiles (2x6m) 1,5x1,5cm. Clear cargo size is 95x65 cm and it's very lightweight. We was test him with app load of 75kg, and it's more then good. Wheels are from some small bike (front and back – 20”), second hand normally completely repaired. Hitch is madded from swivel caster wheel from hardware store with one additional metal plate welded additionally, and it's very simple but very strong (thanks to this) . We was decide to put metal net like cargo floor, because my friend was have couple pcs in back yard, and I think that is good solution even it's add little weight to trailer.
Any way, I'm very happy with results, my kid's too.
two wheels from old bike=3,12$
new tires, axial for wheel=14,5$
two metal profiles (12m) 1,5x1,5cm=11$
bolt, small parts..=5,5$
metal net=free (regular price here approx. 5,5$)
welding= thanks Memet (regular price here approx, 15$)