To build a Styrofoam igloo, cut Styrofoam blocks in half, hollow them out, fill each block with a plastic bag full of water, glue the blocks together, stack them, and shave the outside of the upper blocks to create a dome shape. This three-hour project requires large Styrofoam blocks, a box cutter, plastic freezer bags, water, strong glue, a chef's knife and several sheets of fine-grained sandpaper.
- Cut and fill the blocks
Cut a Styrofoam block in half, and hollow out the middle of each piece Pour water into a plastic freezer bag, and place the bag in the hollow. Stack the Styrofoam halves and glue them back together. Repeat this procedure with the other blocks.
- Create the foundation
Place a single layer of filled Styrofoam blocks in a circle, but leave out the last four blocks so you have room for the tunnel. Lay the foundation for the tunnel by making a straight row of blocks on both sides of the gap.
- Glue the foundation
Glue the foundation blocks together.
- Stack and glue the rest of the blocks
Stack one layer of blocks on top of the foundation, and glue them in place. Lay the third layer, and then push each block slightly toward the middle of the igloo. Glue the blocks in place. Use the same technique for each additional layer.
- Trim and sand the blocks
Use a chef's knife to shave the exterior of the igloo into a smooth shape. Finish it by sanding the Styrofoam until no rough angles remain.