I tried this last year: it works! How to make an inexpensive non-toxic homemade weed killer to control weeds in your garden: 1 gallon of white vinegar cup salt Liquid dish soap (any brand) Empty spray bottle
This type was made over a glass bowl (covered in plastic wrap), with the concrete over it. The stem is a bud vase with the concrete mix over it. These are my new favorite stem, and the easiest! And the bud vases come in some very cute shapes.
DIY Cement Mushrooms: The crown is created by digging a hole in the ground and filling w/ cement, the stem is a two-liter drink bottle w/ top + bottom lopped off. Just in case I ever need a cement mushroom.