How to collect icons for your project from different icon fonts and painlessly connect them?

Question

Icons

It so happened that some of the icons are used from material design icon and some from font awesome. Each of them has missing icons for this project. Connecting both fonts is expensive. How to cut out the icons you need from there and pack them into a separate icon font and use them in your project?

Answer 1

Collect SVG sources and convert them to sprite. This is class correct (fonts are not highly respected), and also convenient (use via USE).