[Gandalf_The_Gray]

I picked a 6L pressure cooker from the cooking school for a test & we were unable to get a ring from a disposable phone sealed inside. I suspect a clever person could design an alternative.

I think that the cell phone idea is "over thinking" it. They have created a bomb in a sealed vessel, they know the event timing fairly accurately, so they used a cheap wrist watch with an alarm function as a timer and some batteries for ignition, and put all the parts into the kettle to become part of the shrapnel.

That way the perp(s) could prepare the devices 24 hours in advance and deploy them in the dead of night (after garbage pick-up of course), then get out of town and watch TV.

Boston could learn from NYC cops and get rid of all receptacles (garbage cans, mailboxes, &c) along the potential target zones. Or they could do as the French do in Paris and convert their "garbage cans" into hardened bomb containment vessels which direct the blast upward and away from street traffic.

Regards,
GtG

[kitchen]

See this?