New resource: follow the Yellow Line to the station next to my sandcastle, and take the Yellow-White spur to a newly built spider grinder! I thoroughly trashed the place before I found a reliable mechanism for killing spiders and not destroying their drops. I filled at least four slots in my inventory with string overnight, but that's also all I had room for. I'll park myself there tonight with more open slots and see what stacks up in the morning.
You can finish your giant sheep now, Kart.
Edit: I forgot - the grinder can be shut down during daytime if you want to poke around inside of it. Go up top and find the wood block labeled 'solar bypass' and remove it. There's a skylight shaft above the spawn block. You'll have to kill anything left that spawned before shutdown, and try not to feed yourself into the trap.
BTW, I play on another server that's handed out admin to everyone allowed on and we can give ourselves anything we want. It's boring since cave exploring is pointless, but it also leads to giant structures. Not quite as satisfying for various reasons.