Here is a collection to customize your Sandcastles with bricks, windows, flags, shields and soldiers. More items will come to make your day in the beach a little more epic. This is just the start :)
I've used Blender to create the items and optimize it test by test to make them easy to print and unmold.
Inspired in the "CreativeTools" sand play set http://www.thingiverse.com/thing:909118
This is just a suggestion, you can print it and scale as you wish. I've printed it with a Witbox 3D printer using PLA filament and Cura to slice it.
Layer height (mm) 0.1
Fill Density (%) 15-25
No support needed.