aaah i see, we're on grenades are we...*queue manic laughter*
right oh chaps lets get to it,
get yourself some pvc piping 1"diameter or so, and some endcaps for it as well,
cut down to 6inch lengths, bung yer end caps on,
get a shedload of metal BB's and a few lengths of newspaper fold newspaper in half lengthways, pour ya bb's in there, make sure they are in a nice even layer 1bb deep between the newspaper, fill as much as you can (bear in mind its got to fit in between the endcaps which overlap the piping slightly)...duct tape them up to keep em sealed, then wrap them round around the pipe, duct tape all around to keep secure and ensure bb's dont fall out.
then you got to make some explosives or simply fill them with explosives, im sure you guys can find that out yerselves...as well as detonators
....trust me it aint hard to find out
this design is nice, because with removable endcaps you can simply slip off the "jacket" and turn your frag grenade into a non metallic blast grenade, its also nice because its small handy and a reliable size, so if filled with something like thermite it'd make nice portable self contained heavy duty lock breaching equipment (though you might need to add some powdered magnesium in the top)....so its open to modifications too
grenades are so frickin simple lol
as for usage pshtf, booby traps....if you need to secure your property, or a perimeter around your property (which is hard especially if its rural) having something both lethal and very loud is useful as it alerts you and neutralises at least 1 threat, and if theres a group of several tight knit people, even better > : D
so in the respect of booby traps grenades are probably better than something more specialised, if you have a claymore mine, you can't really throw it! if you got a grenade you rig it upto a tripwire, or to an eletrical detonator connected upto whatever your crazy mind wants! and they are nice and portable
....plus if you made it and know how it works you can dismantle it and use individual parts if you need to, or you can make tweaks like unravelling your frag jacket and folding it on itself a few times so that the shrapnel is directed
anywho hope some of that helps someone somewhere xD