Based on just a little info, there are a couple of partially intersecting patterns among the NYC and NJ bombings. All the bombs used cell phones as timing devices. OTOH, the NYC bombs were pressure cooker bombs, while the NJ bombs were pipe bombs, using multiple devices in each in an attempt to magnify the effects (only one of the pipe bombs on the race course went off).
So, one trigger type, but two different construction types. However I suspect that if I Googled "pipe bomb" and "pressure cooker bomb" I would find multiple sites with instructions for constructing each. And I'm sure there are instructions on the Internet on how to use a "burn phone" as a timer/trigger. So those basic construction techniques are probably not very useful as clues. OTOH, there may be discernible patterns in the particular materials used, how the parts were laid out, and the workmanship and techniques.
