While downloading the blueprints may not be illegal, any UK citizen who made and owned such a handgun could face arrest, according to the UK's Metropolitan Police.

BBC News

It may not the best weapon in the world - it has reliability and accuracy issues - and it may not be the cheapest - around £5,000 for a 3D printer to fabricate the thing. But it's certainly the most portable.

The total file size for the 3D models to build the weapon? 1,084,069 Bytes. Small enough to fit on a floppy disk.

Most of us send emails with larger attachments every day. Never mind that this gun evades metal detectors - spotting these scant few bytes in the gigabit flow of everyday life is nearly impossible.

There has been an attempt to pull the plans from the Internet. That can't work. Ever.

The way modern file distribution is done is decentralised. As long as you know the hash (the unique code calculated from the file's contents) you can download a file from a Peer-to-Peer network.

magnet:?xt=urn:btih:
6C4089AC6C134F1B2DFF18499658B228D9EB2657

That's short enough to memorise, turn into a song, print on a t-shirt, tattoo onto your flesh, or simply send in an SMS.

You can even split the hash up and represent it as a flag of many colours.

My neighbour has an HP LaserJet with an open WiFi connection. I can print anything I want through it. There's a limit to the amount of malicious damage one could do with paper and ink. But what happens when HP release a consumer grade 3D printer with their typically poor security defaults?

Anyone with a phone could walk down the street, upload to those printers a short alphanumeric string, and all of a sudden every house has an (unwanted) AK-47.

We can't wipe this knowledge off the Internet. We can't force every 3D printer to recognise every potentially malicious shape - nor convince it only to print from an "approved" list. We can't stop people of lax moral character from acquiring and using guns.

Do we accept a world where it is trivial to access powerful weaponry? Do we engineer a change in attitudes so that gun ownership is undesirable? Or do we use ham-fisted legislation to try to censor knowledge in a futile attempt to be seen to be "doing something"?

I think I know which one our rulers will choose - but is there a better solution?