This stand will fit in standard Eley boxes and will help to rise the cartridges enough for comfortable loading.

Printed with Creality Ender 3 V3 SE, with PETG, no supports needed. For smoother top surface I enabled ironing.

Testing with diffrent types of Eley boxes: https://www.youtube.com/watch?v=wJYacXkpISE&ab_channel=Outdoorstuff