Sometimes molecular gastronomy can be a real pain in the ass. Even the simplest of recipes -- and a two metre parmesan spaghetto is, believe it or not, relatively straightforward -- can be sabotaged by seemingly benign requirements, requirements like "1-1 L ISI siphon with the emptying attachment spaghetti." Emptying attachment spaghetti?
Mangled English aside, I have no idea what that might look like, nor have I found a retailer that sells it. The likely reason is simple: the spaghetti attachment is actually a customized piece of equipment designed specifically for (and likely by) el Bulli itself.
Unfortunately, the attachment points to a larger problem with pursuing molecular gastronomy at home generally, and cooking from the el Bulli cookbooks specifically: both require a constant stream of specialized equipment -- equipment that is often difficult, if not impossible to get. The el Bulli cookbooks compound the problem by offering no indication of where, or even if, the necessary equipment can be purchased.