I made my materials several years ago and my kiddos have enjoyed them ever since.

I printed my colored files onto letter size labels.
I laminated the printed side using Walmart's laminating paper (found in the drawer liner area).
Then I cut each square apart and stuck them to foam that I purchased from Hobby Lobby.

I used dark blue for water forms and green for the land forms.
So far they have held up through 4 boys.
For storage I use a tupperware container.

I ended up with a total of 155 pieces...and it still doesn't seem to be enough..LOL

Here is the download link for the files. The originals were made by a dear friend of mine Colleen, I just colored them in for easy printing.

Here is some information on the Imaginary Island.
Sample Lesson from NAMC
What's included with the materials?
Tim Seldin's Imaginary Island Studies

Worksheets that can be used with it:
My Imaginary Island Worksheet