well i hope the feds dont come knocking on my door, but here goes
first the critical mass needed is about the volume of a softball, but that is for the nuke itself, to explode it, you need to surround the ball in external ball of explosives, and this second shell needs to be fired off with compound detenaters, that are wired to a circuit board to fire at the same time, the outer conventional explosive must compress the inner material to start the reaction, if anything goes wrong you might not get complete detonation, but even partial detonation would be impressive. but to fit the whole thing in a suitcase? I dont think so, it would be large, and it would be heavy....how powerfull would the bomb be..... > maybe 200000 sticks of tnt..assume 0ne kiloton?..maybe less, but remember a bomb isnt very effective unless it's force is applied to something... but the technology needed to build this, to polish metal and shit, well if you can find yourself from the feds, good luck, or at least I hope you cant hide from the feds....