I used this high-quality shoe bag as the "core" (see onebag.com) for packing my eBags TLS Mother Lode Weekender carry-on and it worked perfectly.  I fit a pair of size 11 Vans in addition to a pair of flip flops in this shoe bag and still had a little space to stuff the thing with some tiny items.  In the past, I've used a plastic grocery bag to wrap my shoes but those always seemed to get misplaced when it's time to re-pack so I'm happy I have this to stay organized now.