This is what you'll need (I used "swimsuit elastic" because it's a natural color that will match khaki pants, and it's super soft!)
measurements are for size 12 months to 2t, adjust length if you need :)
**It also works with 1" elastic-JoAnn's sells some colored elastic in the notions section
***JoAnn's is also where I purchased the vest buckles-in the notions section
****You can buy suspender clips at any fabric store, I bought my round ones on etsy.
it will look like this (Second photo)
Step 4: Step 3
Now, REPEAT for the other elastic strip. Now you'll have 2 that look this this, (2nd image)