Reduce the weight of a wooden box to carry it on the back

H[ATTACH align="right" width="98px" type="full"]71699[/ATTACH]ello everyone,

I have a somewhat unusual question.
I built a wooden box, it is 60cm(l)x60cm(w)x100cm(h) in size and weighs a total of 30 kg.
The box is intended for a specific costume and is meant to be worn on the back in the spirit of the costume.
30 kg is still within a reasonable range in terms of weight, my problem is that for the completeness of the costume a person has to fit inside this box.
That would bring us to about 85 kg in my example, which again is not so light.

My next step is to make the box smaller, I can reduce it by about 25% and the target person still fits inside.
My question is what else I can do to make it even lighter.
I once thought about making the "lid" and the side walls out of foam, but I am afraid that it won't hold the load if someone sits inside.
Are there any ideas/suggestions on this topic here in the forum?

The box should become lighter … then you will have to make it smaller and/or build it from a different material. Somehow out of sheet metal, can you weld?

Or you change your figure. Make it 80 years old, then the box can pass as a shopping trolley with wheels ;-)

Doesn't a sack work as well?

(Seiten)Parts made of aluminum sheets (available in any hardware store - checkered plate or similar) and glued with plywood or even better, wood decor foil applied on top).

(Page) parts made of aluminum plates (available at any hardware store - checker plate or similar) and glued with plywood or even better, wood decor foil on top).

The aluminum/sheet metal idea is a good one, but the problem is that in the places where this box is used, aluminum/sheet metal etc. is not allowed.

Possible (but expensive) would be a construction made of GFK fiberglass panels / fiberglass fleece. You can use your current wooden box as a mold for it. So similar to building a canoe.

Stable, light, no problem with metal detectors (stadium?)

One could possibly omit the side panels and instead use jute straps as connections. I mean some kind of wide shutter strap. It reads as if it is about a medieval costume. You can safely fall back on the old materials there. They are very durable. But unfortunately they are hard to find. Because they are unfashionable. :( If the lid and bottom are connected, you can still cover the sides with a thin board or stretch fabric over them. Then everything is opaque.