Answer:
It is constructed with a high mass and a high raidus.
Step-by-step explanation:
The rotational inertia I for every object is calculated as:
cMR^2 = I
where c is a constant, M is the mass of the object and R the radius of the object.
So, for a flywheel, the rotational inertia is calculated as:
I =

Then, for constructed a flywheel with the maximun rotational inertia we have to set the maximum mass and the maximun radius.