As Marc said ..... yes you could but it's going to cost you.
By the time you build a one off mold, you could have built the plane.
If you want to see some different techniques that would render a lighter weight airframe (where money is no object) then stop by the Vacuum Infusion demo at Oshkosh during AirVenture. We will be building a fuselage of a new design using Vacuum Infusion and molds. These molds are made from plugs that start out as CNC milled foam ….. so as you can imagine, just building the molds involves quite a bit of technology and $$$. Now, if you were building a kit, then you could justify the expense.
As for the Berkut, I'm sure that we could demonstrate how Vacuum Infusion could reduce the weight of that aircraft considerably, so your point about newer technology and techniques is well taken.