Weight should be considered in selecting the table top material.
Drafting is a vigorous activity, and a light-weight table is not a joy
to work upon. In designing the table base, the question of seating is
paramount. Stool height might be considered preferable to the activity
of drafting; as you must perceive with the eye to articulate with the
hand, stepping forward for the birdseye view is necessary over a large
board surface.
For a three foot by four foot tabletop, two pieces of 3/4 high-density
particle board laminated together with a wood edgeband adds up to about
thrity-five pounds. A professional board cover on top of that makes an
excellent drawing surface.
Making your own parallel rule or drafting machine has the prospect of
an interesting project. Care to try that?