Okay, this line here is incorrect; that’s because this is nil, so it can’t set your customphysicalproperties.
I don’t exactly know what you’re trying to achieve, more information would be appreciated.
script.Parent.Touched:Connect(function(hit)
if hit:IsA("BasePart") then
hit.CustomPhysicalProperties =
PhysicalProperties.new(
hit.CustomPhysicalProperties.Density,
2,
hit.CurrentPhysicalProperties.Elasticity,
100,
hit.CurrentPhysicalProperties.ElasticityWeight
)
end
end)