There are basically 3 ingredients: cardboard, paper, and glue.

First I would make glue by mixing flour with water 1:10 and microwave it until boiling. I'd stir and scrape the bottom every 30 seconds for the first few minutes to avoid burning

The cardboard needs to be kept dry (unless you want to separate the layers). It can be cut pretty easily with a serrated knife. For the first few layers of this box, I cut the cardboard to match the shape of the items. For the final layers, I just took the leftover pieces and glue them on. It doesn't have to be perfect since you can add more paper later. However, cardboard - cardboard bonds seems to be pretty weak, and you can't put too much glue on it, or it will get wet and separate. So I use paper to bind them together.

To get the paper, I spray water down the wavy side of the cardboard (a strong hose seem to work better than a trickle). After that the layers should separate easily. Getting the paper wet and tearing it by hand will give it better edges than cutting with scissors. I would use big pieces of paper on flat surfaces and straight angles, then thin strips for corners and curvy surfaces.

If you need to cut out something from the piece, you can wait for it to dry and cut with the serrated knife. The first version of the box actually doesn't have the hole for the funnel, I actually cut it out with the serrated knife. Then I covered the knife marks with paper

Edit: you can use any cardboard without the glossy surface. The glossy surface doesn't stick to the glue.

I tried acrylic paint, but it prevents me from making adjustments afterward by gluing more stuff on. Maybe I'll try watercolor or felt

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In general, I would glue 5 pieces of cardboard using paper to make the underside of the box. Then I'd put the items in and glue on more layers to fill in the leftover space. After finishing the top layer, I'd leave the items inside the box for a few days to dry and shrink

After that, you can add more paper to make the surface harder, or glue on anything you want.

I also want to know!

Looks like a funnel for filling the grinder with coffee beans.

It's made from cardboard and a bit of egg carton paper

I left a comment here: https://lemmy.world/comment/25979420

My items does look much better when I use the brown paper from cardboard than when I use discarded white paper