is dimensioned for use in manufacturing contact lenses either corneal or schleral from for instance cross linked hydrophilic polymers a spacing of 0 0002 to 0 0005 inches between surface 23 and the lower diameter of surface 51 is utilized the spacing or gap between surfaces 21 and 49 is also in the same range the dimensions set forth in the above example are merely illustrative it has been found that the width of restriction 77 must be sufficiently large so that lens material in reservoir 75 may be drawn therethrough and into mold cavity 73 to fill the void created therein as the original volume of lens material in mold cavity 73 shrinks during the polymer forming reaction the spacing between for instance surfaces 21 and 49 and hence the size of restriction 77 will depend upon such factors as the size and shape of the lens being cast the weight of male member 13 the viscosity of the lens material used and the rate of polymerization desired the faster the polymerization rate the greater the spacing between surfaces 21 and 49 and the larger the size of restriction 77 the fact that during the polymer forming reaction the polymer tends to pull the mold halves together must also be taken into consideration clamping pressure such as set forth in u s pat no 3 222 432 or the prior art described therein is not only not required but would effectively seal reservoir 75 from.