How to prevent losing my design ?

I use metallic and flat pigments in resin to create wall art. But many times I get just the look I want but it sadly flows out and gets lost. Is there a way to lock it in ? Should I be using a different resin ?
I like the self leveling aspect of resin and I like a little bit of movement after I design something since it gives it good flow but I wish I could at a certain point just say HALT !