I recommend to assembly the top and bottom first and then connect the two parts. 

In the stringing guide you can see two guides at the top and at the bottom and in the middle is how to connect the two to one.

NOTE: if you think the stringing guide can bee improved let me know.

Materials Needed

In addition to the printed parts, you will need:

• 1.5mm diameter elastic cord–The exact diameter is not crucial, but you don't want to go larger than this. You also want to make sure the cord has enough stretch to both work with and to make the final toy squishy.
• Something to cut the elastic with.

NOTE: if you think the stringing guide can bee improved let me know.