I had this random idea and wondered if anyone had tried it so thought I'd ask.  Feel free to tell me if I'm talking pish.

WRT envelope bags, has anyone tried one of those bag heat sealing tools to seal up the bag?  If they are good then it'd be dead easy (in my head anyway) slip the part in (ooer) and then just roll over each end and turn on the pump.  Interested to see if its been done.