what country do you live in ?

and when you say 1.5 inches tall - do you mean 1.5 inches internal diameter ?
And have you looked at the plumbing supplies section in your local hardware store ? plastic Tubes and end caps are a staple of the plumbing industry.
All you need to push the soap out is a length of wooden dowel the right diameter or slightly smaller with vinyl tape wrapping used to form the correct size end.

That would be a much easier, cheaper and quicker way of doing this :-)

Tape, tubing and a hacksaw and the jobs done :-)