You can use the already available meshes to make a few new objects by placing the together and changing their size. Then you can put your own texture on them. If you want a completely new shape that's impossible to make with the default shapes, you do need to create it with Blender.
Just turn around from your starting point at Bonfire and you'll see a black hole. That leads to the Ficho Tunnel. Just follow the curves in the tunnel to another black hole that leads to the Flourite Plains. Run straight and you'll see 2 rows of crystals in the water. Swim in between them and you'll get on an island. There's a portal on that island that leads to the Cape. :3