SLA 3D printing or stereolithography is very different to FDM. Prints are still built up in layers but that’s where the similarity ends. With resin printing you have a tank of resin. In our case we only use plant based resins. So, you have a shallow tank of resin. The bottom of the tank is clear plastic. Under that, you have a UV projector. With resin 3D printing, the layers are much smaller. Instead of 0.2mm as you might use on FDM, resin printing uses layers that are typically 0.05mm. Our printers go down to 0.025mm but we tend not to use it as it doesn’t make a great difference to quality. The software to create the files for printing basically slices the model into layers that are 0.05mm thick.

Above the tank is a plate that can move up and down. What happens is that the plate gets dunked in the resin. It first moves down until it’s 0.05mm from the clear pastic bottom and the projector projects the first layer. This cures the resin where the projection hits the plate. The plate them moves up 0.05mm and the next layer is projected. This is completed until you have your model hanging upside down on the plate. Something like a 10mm high model will have 200 layers.