I've always been an advocate of breaking out my ITG / BAP Ultimate slabbed cards - the first one I received was badly damaged in the mail and it literally fell out of the holder.
The second Ultimate card I received then looked out of place in my binders - so I chipped away at the holder until it cracked.
Now the easiest way I've found is to hacksaw the corner where the BGS logo is - or ITG logo for the latest Ultimate - and then prise it open with a flat headed screwdriver
But be careful of any flying plastic shards - they can be bloody sharp
Mal Skelton