Found this today for an alternative toner transfer method without heat. It uses printing to the waxy backing paper from adhesive labels.

What I find really interesting is the design is not being used as a negative mask for etching. The toner is the design, so it's good for etching and as a direct alternative to waterslide decals. But with no decal edges and mess to contend with. And once the transfer is made, just clear coat right over the top.