How to make flexible chassis :1

1.Extending chassis hole in front and rear with 5.5 mm drill.

First, cut the tubes of the chassis about 3mm.

Next, extend the holes

When you extend holes, pierce the chassis.

In normal way, you don't have to pass through, but piercing is easy to make.

Make holes about 5.5mm diameter.

You can find holes pass through. 

Extend holes in front and rear too.

Next, I introduce you about "cutting center chassis".

Thank you!!