It's a modified 3mm "long" pad creqted on the Eagle footprint editor :
-Drill Size 3 mm
-Diameter : Auto
-Milling Layer (46) Contour flush with drilled hole in order to create the oblong aperture, using the line and arc tools
Would have shared the library file, but the file extension is not supported on MW
add support for "long" mounting holes for more tolerant Eurorack mounting
from this ModWiggler post by
abschall
: https://www.modwiggler.com/forum/viewtopic.php?p=3573713#p3573713