I've done something similar in the past, although I just kind of handed them out to people instead of asking ahead of time, which seems like the much smarter idea.

Personally, I've found HP-4 to be the best weave for lanyards, since they lay flat. I've always used larger rings for them too (anywhere from 16g 5/16" to 14g 3/8"), and it goes a lot quicker. I can usually get one done in under two hours.

I seriously recommend shelling out a few buck for swivel lobster claps. They're way more reliable than bulldog claps, and its easier to put badges on.

If you happen to get overwhelmed with orders, let me know. I have some extra supplies and a little bit of free time. I can make a few of them if you need me to.

Here's a few that I put together a few years back (I was handing the blue and orange ones out at PAX Prime).