Yes. I don't know which item to craft. It is choosen between recipes randomly.
Have several redstone torches and light one and only one randomly will also satisfy me (in this case I will export each item in a chest and play with redstone control on conduits to give me one)
Maybe a trick with some items ? I think that dropper choose an item randomly but maybe other mod items will produce random better ?
So, basically, what you're looking for is a random number generator, correct?
If there are no more than nine different items you want to randomly choose from, a dropper may indeed be the best way to pick one at random. If you're OK with keeping a full stack's worth of each exactly nine items as a buffer, you could simply have an export bus craft and export each of them into the dropper, after seeding the dropper with one item of each type. The export bus will fill each stack in turn; and when the stack is full, it won't be able to export any more of those items.
If, instead, you don't want to buffer so many items all the time and instead only want to keep a few on hand, you'll have to make use of a more complicated item-stocking system, like that shown
here. This system is for AE1, but the mechanics involved haven't changed too much. The main differences are that the power relay (which looks like an energy acceptor) is replaced with a quartz fiber, and you'll need to keep track of your channels. If you're stocking few enough types of items that you need no more than eight channels between the storage bus on your dropper and all the level emitters and ME Interfaces, you won't need a controller on the subnet.