How to check if a part touched a model?

You have a few options here...

1 is an ugly method called magnitude, works best on circles:

if (part.Position-part2.Position).Magnitude < (whatever the size of part2 is, any axis) then
    print('in range')
end

You can loop it or whatever.

You can use region3, raycasting, .Touched, GetTouchingParts()

local part = workspace.Part
for _, v in pairs(part:GetTouchingParts()) do
    print(v.Name)
end

You can loop it again for the next time its touched

then theres the good old .Touched

part.Touched:Connect(function(obj)
    if obj:IsDescendantOf(workspace.Model) then
        print('model touched')
    end
end)

You can also do it the other way

for _, v in pairs(model:GetDescendants()) do
    v.Touched:Connect(function(obj)
        if obj == part then
            print('touched part')
        end
    end)
end

So uh, see which one helps you, gl bye

It is currently not possible to detect if it is touching an entire model but instead you can insert a part into the model and resize it until it is even with the model. Then you can set CanCollide to false and set Transparency to 1.

Just detect hits between parts, and detect if its in your desired model. Very simple solution:

if hit.Parent:IsA("Model") and hit.Parent.Name == "YourModel" then