Calibration Piece for Lite3DP-S1

##Problem:
The size of Lite3DP-S1 print bed does not fit the resin exposure test model.
https://core-electronics.com.au/tutorials/perfect-resin-print-exposure-setting.html

But resin exposure need to be calibrated to get a proper result.

##Solution:
Since the resolution of adjustment of Lite3DP-S1 firmware is 1 second only, we do not need all feature on the piece to complete the calibration.

I extract the most essential session of the test model. It require minimal volume of resin and able to finish within 10 minutes for 0.05mm resolution.

##Usage:
The ZIP file contains the converted BMP file for Lite3DP-S1. It can be used directly without slicer. Use the STL file if you want to test your own slicer.

Start with 60 seconds for initial layer and 5 seconds for other layers.
If the base is a perfect square and the piece stick to the build platform, then the exposure for initial layer is just right
If the tips of the "infinite" symbol just touch each other, then the exposure time for other layers is just right.