The hardware is available from specialty hardware and woodworking stores . The name of this special type of hinge is a "lid stay" or "flap stay", or "lid support" .
See a variety of different kinds here:
Specialty Cabinet Supplies - Lid Stays
and here:
Rufkahr's Lid Supports
This kind available from Rufkahr's is called the X-70200/05Z Lift Up Ratchet Support.
Another kind of table support used is a Pneumatic Spring Stay :
In these photographs you can see how the Lift Up Ratchet Support is used to make a portable animation table , similar to this one : Portable Animation Table Plans, but with the lift up supports.
In the following photograph of animator Børge Ring's animation table you can see the Pneumatic Spring Stay used to hold the table top at the proper angle:
