Check out info on resin casting. You have a mold, mix the resin with a catalyst. Whatever is in the mold gets embedded in plastic. - This link doesn't include info, but it's a reminder to go check out more info on resin casting
DIY Tree Branch Seahorse **Mi(my) WAY: combine with the idea of the lit wood Christmas tree on the canvas, do any shape on the canvas then add lighting. Or weave lighting through out or around the seahorse or whatever u design.