If you have some brick and a couple of pizza stones, try making a pizza oven. No...

If you have some brick and a couple of pizza stones, try making a pizza oven. No mortar, but puzzle it together.

Here's a profile:

                                                                                                       +--------------+
   +--------------------+                                                  +---------------+           |               
   |  Top Pizza Stone   |<--+                                              |               |           |               
   +--------------------+   |    +-----------------------------------------+               |           |               
                            +----+-----------------------------------------+-----+---------+-----+     |               
   +--------------------+           .-----------------------------------.        |               |     |               
   |       PIZZA!       |<---------(                                     )       |               |     |               
   +--------------------+           `-----------------------------------'        +---------------+     | <--These are  
                                 +-----------------------------------------+     |               |     |  all brick    
   +--------------------+   +----+-----------------------------------------+     |               |     |               
   | Bottom Pizza Stone |<--+    +-----------------------------------------+     +---------------+     |               
   +--------------------+        |                                               |               |     | Note the gap  
                                 |                                               |               |     |at the back of 
                                 |                 X       X               +-----+---------+-----+     |  the bottom   
                                 |             X  / \ X   / \X             |               |           | pizza stone   
                                 |            / \/   \ \ /   \\            |               |           |               
                            +--->|           /  |     | |     |\           +---------------+           |               
   +--------------------+   |    |          |    \   /   \   /  |          |               |           |               
   |      Fire Box      |---+    |           \   /\ /   / \ /  /           |               |           |               
   +--------------------+        |       +----\ /--V-\ /---V\ /--+         +---------------+           |               
                                 |       +-----V------V------V---+         |               |           |               
                                 |                                         |               |           |               
                                 +-----------------------------------------+---------------+           +--------------+

View from the front:

                 +---------------+              Upper stone                +---------------+                           
                 |               +-----------------------------------------+               |                           
                 |               +-----------------------------------------+               |                           
                 +---------------+  .-----------------------------------.  +---------------+                           
                 |               | (                PIZZA!               ) |               |                           
                 |               |  `-----------------------------------'  |               |                           
                 +---------------+-----------------------------------------+---------------+                           
                 +---------------+-----------------------------------------+---------------+                           
                 |    Bricks!    |               Lower stone               |    Bricks!    |                           
                 |               |                                         |               |                           
                 +---------------+                 X       X               +---------------+                           
                 |               |             X  / \ X   / \X             |               |                           
                 |               |            / \/   \ \ /   \\            |               |                           
                 +---------------+           /  |    FIRE!    |\           +---------------+                           
                 |               |          |    \   /   \   /  |          |               |                           
                 |               |           \   /\ /   / \ /  /           |               |                           
                 +---------------+       +----\ /--V-\ /---V\ /--+         +---------------+                           
                 |               |       +-----V------V------V---+         |               |                           
                 |               |                                         |               |                           
                 +---------------+-----------------------------------------+---------------+

Tips:

Try to use as few bricks as possible - say 30, but extra points for as few as you require to build

Square pizza stones are easier to build with - but round can work too

Takes about 25 minutes to get to temperature of 800f but careful, it can get to much more and your pizza with simply burn

Fire brick takes much longer to heat to temp

Wood peel to place pizza and metal peel for taking out

Rebuild often and without reason