Help with interior

ok so i need to make like 4x4 1/4 inch steel plates and weld them to the floor over each spot where i drill holes and use flat washers and lock nuts thats what i have to do correct.
Thats the plan.
I could come up with a pic of OEM plates installed and even add dimensions if you are serious about making your own.
You could predrill the 1/2" holes in the plates and drill the holes in your floor pan where the factory dimples are.