Many years ago I restored (and replicated) some eighteenth-century furniture that involved a fair amount of harewood (green-dyed Sycamore) and other coloured veneers. The only coloured veneers available commercially were far too thin, so I cut my own veneers and dyed them.
I bought a second hand aluminium pressure cooker from a charity shop and had a friend part the rim off the main pan on his lathe (although I could just have easily done it myself with a hacksaw). I then took it to a sheet metal works where they rolled a cylinder from sheet aluminium of the same gauge as the pan and then TIG welded the cylinder to the pan and rim.
The result was a pressure cooker that could accommodate 30" x 10" sheets of veneer. For safety's sake, the modified cooker was first brought up to pressure outdoors on a gas burner, well away from everything and maintained at full working pressure for about fifteen minutes.
In use, I filled the cooker with water miscible aniline dyes which, under pressure, fully penetrated the 5/64" veneers. From memory, the total cost of the pressure cooker was less than $100 - probably much less than the cost of shipping veneer from Europe.