We moved rearward to tackle the floors after getting our front end was largely under control.
Mini Mania sells full floor pans, so we ordered floor pan repair sections from them. We only had rust in the front half of ours, though, so we replaced the front driver’s floor pan and just used a small patch on the passenger’s side.
We decided to seam the repair under the large brace that separates the front seat from and back seats. Welding in this area is impossible to detect from the top of the car, especially once we grind and seam seal the bottom.
First, decide how much needs to be repaired. Next, carefully cut out the rusty metal. This is generally done with a reciprocal saw, rotary cut-off wheel or a plasma cutter.
From there, cut the patch panel to the correct size, making sure all the metal is clean. Then start seam welding in small bursts, allowing the metal to cool in between welding sessions.