Paper doilies made to be used as liners on cake plates and cookie platters make great stencils for painting the illusion of lace.
You can find these doilies in grocery stores, and in the department stores cake decorating departments. They come in a variety of colors, shapes and sizes.
Most of the white paper doilies are very thin and are fairly obsorbant, so you have to be careful not to use too much water when painting over them. I've found that the gold and silver metalic foil doilies are slightly thicker and work better when they get wet.
As shown in the photos you can use a brush or a sponge or even a damp paper towel to dab over the holes in the doily. Another option is to use a fine mister filled with diluted watercolor.
When working with these paper doilies as stencils one important thing to remember is that you use very little water.
I sometimes spray the doilies with clear acrylic before I use them to make them hold up a little longer.
I'm always on the look out for plastic doily placemats or table cloths in variety stores too. They can be reused several times.
I hope this gives you some ideas for making your own watercolor Valentine cards. Have fun! SUSIE