I put a digital indicator on the resin tank and allowed it to do a couple peel cycles. The far right edge moves down approximately 7 mm. It doesn’t look like the left edge moves much at all. That means that the resin tank moves down about 6.25 mm (~0.25 inches) at the rightmost edge of the build platform. I would say that is a realistic minimum depth that we’d want the resin to be at to ensure our parts are always submerged making it impossible for air bubble to get underneath. This is a worst-case-scenario for parts on the right side of the build platform. Parts farther toward the left would require less depth.
To me it looks like the distance between the minimum fill line and the maximum fill line is about 10 mm. You can use that as a guide to estimate 6.25 mm. If you wanted to get really high tech you could also add a mark to the sticker 6.25 mm up from the silicone.
There are more factors at play than simply the amount the tank moves down. As to not nerd-up this post too much I’ll just make this short. If the resin had incredibly low viscosity you could theoretically let your depth get down to ~3.5 mm (assuming I did my measurements, math, and 3D drawing right). At 3.5 mm depth the “top” of the part would basically be at the exact same level as the surface of the resin (again, if I did my measurements, math, and 3D drawing correctly AND if we were dealing with incredibly low viscosity resin).
In my drawing the white is the tank, the light blue is the silicone layer, the dark blue is what 6.25 mm of depth should look like at the apex of the peel movement, and the red line is the level the cured resin would be at.
Anyone wanna double-check my measurements and stuff?
