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hot glue gun
Any hardware store such as Brico.
They have this on their website, but if you go there, they have more choice in store.
http://www.brico.be/wabs/fr/catalogue/p520001/pistolet-a-colle-pkp72li.do
Depending on your useage, you may also find smaller and less heavy duty tools in large office supply and stationary stores such as NIAS or Schleiper.