My simple build. Old TM driver shaft, 4mm phillips screws (to match the number of washers) 16 , 21, and 26 washers for 253g, 295g, and 336g total club weight of the shaft and washers .
Used a small lock washer at the head of the screw, small fender washers at the top and bottom (1/16" hole x 5/16" dia), and big (3/16" hole x 1 1/4"dia) for the weight. 8g each.
TM Fujikura XLR8 Reg flx from M2 driver. Might switch to Senior flex.