This won’t answer the original question, but I have a set of jesel .937 keyway lifters. Without any assistance from a scale, it is easily noticed the weight difference between a .904 tie bar set of lifters compared to two of the larger .937 lifters. Although some of this weight is in the tie bar, rivets, and extra height, the general body on a standard roller lifter is thicker all around.
The jesel lifter doesn’t need the additional height. The bodies are much thinner tool sleel. And the pushrod contact cup is can be installed for offset of the pushrod.
It is clear that jesel did put in effort to lighten the lifter.