Unfortunately, building a made-to-measure last is an extremely rare skill these days, requiring a great deal of time, labor, and expertise. Anyone you could go to with a legitimate level of skill will likely charge in the thousands of dollars range for a custom last.

A cheaper way these companies can size larger feet is to take an existing last and build up material over it to meet your measurements. This may cost in the $50-$150 range to get sized as opposed to the thousands of dollars range. The downside is that they can only build up so much material on the last, so your feet may be too big to go with the less-expensive option.

Whichever route you end up going down, I hope you find a solution that works for you. This really is a difficult challenge to solve.