Create a router plane from a chisel
This is already done by creating a hole in a board and then jam a chisel in this hole; but it is a clumsy and imprecise.
There are also already perfectly good router planes but they are expensive and have only one cutter and hence only one width.
But… as a carpenter one has a bunch of chisels. So why not have a holder for them that does what a router plane does? It is probably not as good as there isn’t any flat part of the cutter against the wood but for much of the work it should do.
Take this idea further to a rebate or shoulder plane.