If you have anything of value, trade for them.
If you lack a shovel, wine/beer/tobacco in plenty and 2 chests, trade for those.
I usually have an alt with a HF at the clay node, dig a bunch of clay, put in clay cauldron signs, port them back and forth from village idol, burn them at village and port them to the building site with another alt with a HF the building site.
If you don't have a village idol you could burn at the clay node, but it'll be a major pain.
A very helpful bug is to hold a shovel and start digging, while you're still digging take off the shovel and put on two traveller sacks, you will still dig at the same speed and stamina drain, but helps with the inventory space.