print with tough PLA or similar Material (Material requirement: no stringing, durable enough, should soften in hot water)
print in place (as large as possible ;) , use high infill, will be still formable in hot water)
soften in warm water bath (caution with hot water)
press against windshield (caution: the temperature difference shouldn't be extremely high, don't try to press a half-molten print against a ice cold windshield, do not heat the print with a lighter or head gun)