My vise production method…

I start with a sheet  of 8 x 4 foot  best-quality 12 mm thick ply and get it cut into 6 rectangular strips. There is some left over.  Often the timber supplier will have a table saw and will cut for you. I recommend best quality ply because it will have less air-gaps and so be stiffer at the jaw-line. Stiffness makes filing much more predictable. 

Note an axle-bolt at bottom right of image below. That allows the vise to rotate to just the right angle and the right height for you.

4 curved vise cheeks awaiting assembly. Axle bolt bottom right.

Cutting list

Whatever vise length you opt for, cut your ply  to these widths:-

6-cheek   viseNowidthtotals
inside cheek2250mm500
middle cheek2229mm458
Outside cheek2208mm416
tool tray floor1150mm150
Cantillever fillet130mm30
Cutting list for vise jaws

Make a curve

The curve of your vise should match your most commonly-filed saw. Improvise a compass …