This is the idea:
Thereare things I already have.
720cm 2 by 4
780cm 2 by 4
760cm 2 by 4
65cm by 450 cm ply
65cm by 100cm thinner ply
1m by 550cm astro turf
2m pvc pipe
2m pvc pipe
nails
Four 180cm 2 by 4 suporting a 65cm by 65cm piece of ply, underneath the ply at the middle of the posts and base 65cm 2 by 4. In diagonal going down to the ground two pieces of 230cm 2 by 4 holding 65cm by 230cm ply beween them, wich is suported by four pieces of 65cm 2 by 4. Then bent piece of thin ply 65cm by 100cm for transition. 65cm by 200cm ply on top of crate. Thick pipe 200cm with a thin pvc one 200cm on each side.