Yes it is called sandcasting. Its used for a lot of different materials including iron and bronze. I don't know how much fidelity you would get from just pressing an object into sand, pulling it out, and casting. The sand needs to be packed very tightly. I haven't cast hypertufa but I usually take the form and make a wood frame that surrounds it. The form is placed flat on a flat surface with the frame around it and the wet sand is packed very tightly into the frame with a tamp. Than I screw on a back and flip the mold. Remove the form and your have a mold. That's the basics.

I believe it would detract from the often subtle beauty of buff beauty. The color of rosarium ueterson can vary from a bright raspberry pink to a flatter almost coral shade I'm familiar with it as an espaliered 7x7 beauty.

It grows among other plants in nature. Whether it will fit into your garden depends on which type of milkweed you are growing and what type of garden you have. I've grown mostly A. Incarnata and A. Tuberosa which stay in pretty well-behaved clumps. The incarnata reseeds generously, but are very easy to pull in their first season. Does that answer your question? Martha

I never totally bury the crinums on first planting. They will adjust themselves. Some like to grow much deeper in the soil, some not. I always plant them like an amaryllid, neck and shoulders above the soil line, at least in clay I do. I've never planted an amaryllid in anything else. Mine all seem to do great!