Bias binding is a b*tch

I'm currently trying to make a little box out of fabrics (including heavy weight interfacing) as well as another skirt. And in the interest of learning new things, I decided to use some bias binding - on the box to line the edge and on the skirt to add some colour.

I should have listened to my teacher! She had suggested making your own bias binding, rather than buying it. The red satin one I bought was not only difficult to work with, but then also frazzled and got all ruined. Which is really annoying, as half of it looked really good...

the bit that worked - and where it all went wrong...