What you will need:

1. Garlic crusher
2. Smallish boilies
3. Tight-fitting jar or container

Step 1. 

Take your garlic crusher and place 1-2 boilies in it. Squeeze the handles till worm-like bits of boilies comes out.

Step 2.

Place your jar underneath your garlic crusher and scrape the worm-like particles into the jar.

Step 3.

Do this till you have a considerable amount of particles in your jar.

Step 4. 

Put your lid on tightly and shake the jar-container for a few seconds.

Step 5.

Take the lid off and voila! You have crumb.

Links for tools.

https://amzn.to/38sYi41

https://amzn.to/38w1LyF