The elastic gathering foot not only takes the hard work out of attaching elastic, it is also great for making your own custom soutache.

The three (optional) attachments allow you to sew 7.5 mm, 10 mm or 13 mm flat elastic directly onto fabric -

Elastic Gathering Guides
7.5mm Elastic Gather Guide - 200805102
10mm Elastic Gathering Guide - 200805205
13mm Elastic Gathering Guide - 200805308

Adjust the screw to control the amount of tension or pressure placed on the elastic being gathered