© Helen Murray

Matthew Robins' Iron Man is a cardboard giant. He stands centre-stage, 15 foot tall, a stack of boxes sticky-taped together. His rectangular arms hang by his side, each finger three gift boxes joined and jointed. There are two circular holes where his eyes should be, no mouth below, and he looks – god knows how – every bit as sad as Ted Hughes' scrapheap colossus should. The Iron Man is one of a kind. He's lonely and he's misunderstood.

His story starts, here, with a suicide attempt. A shadow puppet steps off the side of a cliff. The Iron Man topples and breaks apart, before his limbs put themselves back together. Angular hands scuttle around on itchy fingers. They roll papier maché eyeballs back into their sockets. Legs sit themselves up and arms haul themselves back into place. It's creepy – all manner of Frankenstinian hybrids emerge – and when the Iron Man stands reassembled, eyeball to eyeball with the balcony, he is as threatening as he is friendly.

This is the monster that crunches across the countryside, chewing up tractors and flattening barns. He towers over tiny farmhouses, until local farmers lay their trap. This is an outcast's tale and it ends with the Iron Man's ability to take pain.

One forgets how strange Hughes' story becomes. It spins off with the arrival of a space dragon, conceived by Robins as a fright of movement – a dervish in a devilish mask whirls in firey, flickering lights. He flies off into the sun and the Iron Man lies still on a bed of fire. Whosoever takes the heat wins the day.

Cardboard is an inspired choice. Hughes' tale mixes mettle with fragility, steeliness with vulnerability, and flames might chew through this Iron Man. Robins zooms in and out. The Iron Man can be both big and small; lumbering in person, delicate in the silhouettes of shadow puppetry.

And just as the adult world casts cast iron away, kids discard cardboard. Yet, as any parent will tell you, boxes can be far more fun than their contents, and so it is here, a thousand times over. Robins animates these off-cuts brilliantly. Puppetry can do what poetry does. Both can bring inanimate objects to life. Both combine things to make more of them.

Told in snippets, Robins' show might stutter, clunking from one scene to the next and creaking between set-pieces. It could dearly use a dab of lubricating oil, but it's still soulful and melancholic. More than that, it will make kids want to make all-sorts for themselves.

The Iron Man runs at the Unicorn Theatre until 5 March.