3d printing from a pool of liquid resin

That must be it. The top layer of resin is hardening. The excess we are seeing in the video (on top of the water) will be consumed as the print progresses. Peachy has some interesting math to solve to get consistent prints. As the printed object is immersed in the water the resin pool on top of the water will get thinner. This does not present a constant resin pool depth as the water rises. The amount of resin pool decrease depends on the solid area of the printed image and will be a different factor for different prints. I applaud the Peachy team. It's an interesting concept but one that I think will go nowhere. To stay in their price goals requires the hobby-grade laser light show mirrors that will require constant tuning. The device itself will require Gibraltar grade stability and it will be a bitch to setup for each print and cleanup afterwards IMO.