Compression-fit Spool Bushing v2
This is a compression-fit bushing you can use to mount your spool to a spool mount/holder. It fits Ultimaker and ProtoParadigm spools. Has 8mm hole for a smooth rod in order to attach to a spool holder such as this: thingiverse.com/thing:20663
Print one or two (two gives better stability) and insert into your spool. May require force.