> He uses a squeeze bottle commonly used for ketchup or mustard ...

You can get 'clear' plastic squeeze bottles in any craft store (e.g.,
JoAnn Fabrics, AC Moore, Michael's) in the 'Wilton' products section
(cake and candy making supplies).  The squeeze bottles are used in
candy making and can hold up better with 'heated' medium inside.

Nancy Fratti - Nancy Fratti Music Boxes
Canastota, New York
http://www.nancyfrattimusicboxes.com/