These designs are a series of chucks for KW spin coaters. Three of them are adapted for silicon fragments of different sizes. They use O-rings of different sizes. The size is indicated in the file name with the first dimension being the outer diameter and the second dimension the ring thickness. O-rings are not strictly necessary for being air-tight, but mostly to increase the friction coefficient between the chuck and the sample. Two more designs are adapted for glass slides and include a recess to center and maintain the sample. In this case the O-ring is not strictly necessary (the recess is enough to hold the sample) and one design does not use one. I have tested all those designs printed in PLA tough with 3 walls and 25% infill up to the maximum speed of 10 000 rpm without issue.