Like the Christmas shoe bomber, he had gathered enough expoldable stuff to actually make a bang, but his detonating technique was dismally short of being effective.
I watched a video of the NYPD bomb squad removing those three propane tanks. They were similar to the below one shown:
This is the kind we Americans buy by the millions to use with outdoor barbecue grills.
Propane is used as fuel in cooking on many barbecues, portable stoves and in motor vehicles. The ubiquitous 4.73-gallon (20 lb.) steel container is often dubbed a "barbecue tank" (used in making a Hank drum). Propane remains a popular choice for barbecues and portable stoves because its low boiling point of −42 °C (−43.6 °F) makes it vaporize as soon as it is released from its pressurized container. Therefore, no carburetor or other vaporizing device is required; a simple metering nozzle suffices. Propane powers some locomotives, buses, forklifts, taxis and ice resurfacing machines and is used for heat and cooking in recreational vehicles and campers.
So... It's readily available just about everywhere and this doofus had no trouble getting his hands on three of these "barbecue tanks" for his "explosive" devices.
Beyond that though, his attempt a bomb-making became laughable.
Along with the Christmas underpants dude, his attempt at terror indicates he was encouraged to do the deed by a group of foreign America-hating uneducated idiots who couldn't assemble a working garden rake.
If this "attack" is now typical of today's kind of terror attempt, we have indeed cut the head off the snake of international terrorism.
But be cautious... Very smart, dedicated and well financed people are still out to do us in. Sending over an idiot with an unworkable plan every now and again may be just the ticket to get our guard down, to get us laughing at their pitiful attempts, at their stupidity. Smoke and mirrors, smoke and mirrors.
Just as in 9-11, we will probably never see the serious guys coming.