Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:6269202.

Flow calibration squares to test different flow rates.

You should do an extruder calibration first before tuning flow.

I use these flow calibration squares to find the best flow and layer height combination.

Slicing with Cura To slice the .stl in Cura 5 with custom flow settings per tile:

1. have the Mesh Tools plugin installed
2. load the Flow Calibration.stl
3. select the model, right client and select Mesh Tools > Split model into parts
4. delete any tiles you don't need
5. select a tile and click the Per Model Settings option choose Select Settings, filter for the Flow setting and select “Flow” and “Initial Layer Flow”
6. adjust the flow values to match the number on the tile
7. repeat for each tile. Slice with a 0.2mm layer hight

Try to get the 100% flow to be the best by adjusting the Z-offset to reduce or increase squish.

Slicing with PrusaSlicer Not currently possible as far as I can tell. PrusaSlicer sets the flow (extrusion ratio) in the filament settings, it's not possible to set a flow override per object.