Spell Packets?

What is appropriate for fastening? Are rubber bands OK or not environmentally friendly enough? Should string be used, like kite string?

Regular household cotton twine is probably best. A double square knot usually does the trick. I recommend wearing dexterity gloves if you're going to be making a large quantity such as a service donation, or your fingers will pay the price from having to tie 500+ knots with thin twine.

Both have and are currently used. Many elastic bands degrade. IIRC, more SPs are offered for the ones that are tied, as they take longer to make. The exact quantity of SPs per packet and type will have to be listed by someone from Logistics.

Fabric stores sell a wheel (pizza cutter-like) device that makes it very easy to score/cut material. One can also by a plastic "fabric" mat upon which to lay the cloth prior to cutting. While this will involve some up-front costs, if one is going to eventually make thousands of packets (I have), it really cuts down on the time.