Any Lowepro case with a "sliplock" attachment should fit it.
Just checked and none of the current Toploader range have sliplock attachments on the back.
You'll need to use the Toploader shoulder strap / harness, or just use an ordinary belt.
Looking the photos on the ThinkTank website it might work - the belt loop looks quite wide.
But you might be better off getting the ThinkTank belt to make use of the rotate functionality.
http://www.thinktankphoto.com/products/digital-holster-50-v2.aspx
Tell me how wide the belt is and I'll measure the loop on my Toploader tonight.
Thanks for letting me knowIt won't fit then. Belt loop on my 'TLZ mini' is 7cm.