Read news reports on detention of 19-year old Russian national Vladislav Miftakhov in Pennsylvania on suspicion of building/possessing home-made bombs and pot.
Hard to discern his motifs, of course, given the scarcity of information, but it looks like an 'explosives junkie' rather than a lone terrorist.
Judging from how his classmates and acquaintances describe him, Miftakhov appears to be asocial, 'weird,' but there is nothing that would indicate he is a terrorist wannabe.Yes, his last name is Tatar and Islamists from that ethnic group have participated in terrorism activities in Tatarstan and North Caucasus, but there is no publicly available evidence so far that would let me conclude that Miftakhov is either an Islamist or harbors any grievances against U.S. authorities or populace. The Tsarnaevs also smoked pot (Islam prohibits consumption of alcohol) and experimented with explosives, but they were doing the latter with a specific practical terrorist purpose in mind whereas this teenager appears just to love exploding things.
Such a hobby may explain his interest in pursuing an engineering decree, but it is, of course, unhealthy and could have eventually lead him to start blowing up objects with his home-made bombs to get kicks out of it, pretty much like those suffering from pyromania 'progress' from small yard fires to setting entire buildings ablaze.