An elderly family member asked if I could make a 3D foot mat to improve their foot circulation. Looking at thingiverse, i found these things are called accupressure devices. I looked at all the designs and found the best device was: Bed OF Nails dot by ssaggers on Thingiverse: https://www.thingiverse.com/thing:98924

I printed one of these things and gave to my subject for testing. They said it was perfect but they wanted for their whole foot and not deal with sewing it to a fabric. I took the original design and re-did to a generic 100x220mm mat size that nearly maxes out my Ender3 Pro bed.

Printed in ordinary PLA
HEAD: 0.4
LAYER: 0.3
LOWER: 1
UPPER: 2
PERIMETER: 2
INFILL: 20
TEMP: 220c

Overall printing at 0.3 adds speed to print and gives really nice finish without super sharp tips that feel good when I push on it with my fingers. Make sure your filament is NOT BRITTLE. Some manufacturers have little flex. I found some cheap PLA on Amazon that has very good flexibility and prints nicely. Since this thing is stepped on, its got to have a little ability to flex under load of your foot. On a hard floor or laminate it should be fine. Not sure about mileage on carpet. If you go that route I highly recommend choosing PETG.