In the series "A Modest Proposal," my colleagues and I will propose inventions and projects that I think are eminently doable and would love made real.

The world is witnessing a revolution in 3-D printing, where one can feed machines blueprints and have them conjure virtually whatever you want right from a dazzling variety of materials — plastic, ceramic, bone, glass, steel, titanium and even more unusual ingredients such as sugar, mashed potatoes, chocolate and living cells.

In June, a portable 3-D printer was announced, one no bigger than a carton of milk and only 1.5 kilograms (3.3 lbs.) in weight. That made me wonder — is a pocket 3-D printer possible, one the size of a paperback book or a pack of cards?

A variety of pocket 2-D printers currently exist, with which one can dash off photos, stickers and cards, kind of like having a miniature stationary store. I might wonder if a pocket 3-D printer might be more like a miniature hardware store or even candy shop. You could feed it blueprints wirelessly with a smartphone.

Creating pocket 3-D printers could be a real challenge, perhaps an insurmountable one. Their key parts might not be miniaturizable enough, or they might require too much power for even the best of batteries, or they might need more stability to work than getting stuck on the go in a pocket could provide.

There's also the question of what pocket 3-D printers would even be useful for. I would imagine they could only manufacture objects the size of maybe a pack of gum or candy bar. I do think a pocket 3-D printer might be attractive if it could manufacture electronics — since 3-D printers are already getting used to make robotic insect wings, maybe a pocket version could whip up little droids on the fly.

There's never any telling what use a technology is useful for until it gets in the hands of the public. And isn't the possibility of an ultimate Swiss Army knife an intriguing one, a device that acts like a Star Trek replicator enabling you to materialize items from your pocket like a magician?

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