[rajnathani]

For very thin stencils, I doubt plastic 3D printing or even laser-cutting plastic works, as such thin plastics would deform rather than remain flat-ish rigid like steel stencils.

Also for 3D printing solder paste, this technique is called solder jet printing. But it isn’t very popular in the industry (despite being less wasteful) due to it being slower than stencil solder printing.

[jazzyjackson]

There’s a minimum feature size of course but for the larger end of surface mount I’ve had good luck with a cheap craft cutter (silhouette cameo etc) cutting a stencil via vinyl sticker, one time use but for the prototyping stage nice and quick.

Laser etching plasticized Mylar (anti-static plastic bags electronics get shipped in) worked well too; because there’s a metal grid embedded in the plastic so you vaporize plastic but small features hold together.

[amelius]

I also wonder how well it works.

When I manually try to squeeze solder paste from a syringe it often doesn't stick on the board (unless I preheat it but that is more cumbersome if there are components on the flip side of the board).