What is "fusable interfacing" and who uses it to make kilts?

[St. Amish]

I also have trouble setting the coffee maker.

[Dixiecat]

Okay, so it doesn't work as well for me. I am also by no means a tailor

Neither am I.

Here's my 'rules' for interfacing:
1) match the weight of the interfacing to the weight of the fabric. Generally, the heavier the fabric the heavier the interfacing
2) match the weight of the interfacing to the 'presentation' that you wish to achieve. -you may wish to have crisp collars and cuffs so use a stiffer weight than what you put in the button band of the shirt
3) test several weights of interfacing with your fabric to see which is best
4) pre-shrink your interfacing before using -place the interfacing in a basin of hot water (hand hot, not boiling hot) and let cool, gently squeeze out the water and hang over the shower rod to drip dry
5) never 'iron' on the interfacing, always 'press'. This means use an up/down motion with the iron, never sideways or back/forth.