Here are links to possible suppliers of
for use as X-ray window materials.
Kinematic bases: see Thorlabs .
Rectangular glass capillaries from Hilgenberg: we are often making use of rectangular glass capillaries, typically 80 mm Length, ~ 0,125 mm wall thickness, 4,2 x 1,25 mm outside dimensions (article no. 1408963). See this picture as example:
.