cLones How big of a room are we talking? Or more precisely, how big of a barrier do you need to make? Yes, hanging blackout curtains with mylar on both sides will be ok, but you'll spend a lot of time patching light leaks. Better to go to home depot or lowes and get some 4x8 sheets of styrofoam (they sell it nest to plywood and such). Clone in a corner of the room, and close off the open side with the styrofoam. You can make a roof for it too, bam, instant cloning chamber. Depending on how stron your lights outside the clone chamber are, you may need to double layer the styrofoam, HID lighting can shine thru it. Good luck
Bro check it out.. you know that black and white poly you can get at the hydro store? well I got a 100x10 ft roll and all you do is measure your walls and cut the piece, double it up at the top and use a little staple gun to secure it to the cieling, in that last post I made you can see the walls of that space, they are the white side of the poly and that little veg room is portioned off in a bigger garage/shed area. It's a good way to do it, you just over lay it at your entrance and kinda separate it to get through.. works well and seals light in well also...
a big cheet of plywood or something simple like that, with each side covered in mylar or painted white will be as good as it gets for cheap.
if you cant find a roll of mylar, you can get those shiny emergency blankets. those are made of mylar
you could just staple black pvc plastic between the two, you might have to get a 2x4 and prop it up to make some kind of frame to hold the plastic up but its a good and effective way to section off your veg room and flower room. And when stapling it use little peices of cardboard from a box between the staple and the plastic so the plastic doesn't rip.
wood? measure the area you need to cover, and then cut 2x4's accordingly and attach white painted stucko/plywood board to both sides.... if your a hand carpenter you'd be looking at an hour tops