Anyone who is interested in duplicating stocks should have a look at how a Dakota duplicator is made.
They're hardly rocket science. The supporting frame is basic ironworking (drilling, bolting, welding) and them for true bearing surfaces of the pantograph, they use round linear ways. If you don't know what a "linear way" is, google them and learn how modern machines ways are made. Hint: CNC machines don't use prismatic ways any more.
All that is necessary and remotely complicated are the bearings and assembly of the pantograph head.
I'd reckon that one could assemble one for less than $4K in iron, aluminum, fasteners and linear ways. Last I looked, the price of the Dakota dupe machine was over $10K.