It is a biological fact that wombat faeces are approximately cube shaped. Wombat poop: Scientists reveal mystery behind cube-shaped droppings
It is also the case that wombats tend to make piles of poop although these piles are somewhat random in shape.
In a fictional world wombats have evolved to be more and more intelligent and have now reached a stage where they build actual houses and enclosures from their cube-shaped droppings.
How can the wombats make effective door furniture (hinges, latches etc.) purely from natural materials?
There is no contact with humans or other intelligent life-forms.
The wombats are pre-stone-age (they cannot shape stone) so everything they make must be of natural materials from their local habitat. They have not yet discovered the secret of fire.
Wombats make mortar/glue for their structures by eating a plant that gives them diarrhoea. They poop this between the layers of 'bricks' to stick them together. A so-called "dry" wombat and "wet" wombat pair can build as a team.
To a limited extent, they can pour diarrhoea into crude moulds that are left in the sun to dry.
Smaller artefacts such as tables and chairs can be made from gluing together the smaller droppings of juveniles.
Rather annoyingly for them, the wombats have developed opposable thumbs on their hind-feet but not their fore-feet. By making a hollow in the ground, they can lean back and use all four feet to do reasonably difficult things such as tie basic knots.
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