This build will have dimensions of 5 by 5 by 5 blocks, it will make a beacon for inside of a Lighthouse. Yaaay! :{P

What we need:

Button x1, Lever x1, Redstone Dust x1, Redstone Torch x2, Repeater x8, Glowstone x8, Sticky Piston x9 & blocks to build with (I use Wood and Cobblestone you may possibly want Black Wool for aesthetics later).

1.

Place two blocks down as shown above; place a Lever on the front face of the left most block and place a Sticky Piston facing upwards to the left. Place a Redstone Torch on the left face of the right most block and place a Button on the front face.

2.

Place a block on top of the Sticky Piston, place two blocks above the Lever block and Redstone Torch. Place Redstone Dust and Redstone Torch on top of these blocks as shown.

3.

Place blocks in an alternating pattern, up and down around as shown above.

4.

Place repeaters so they go into their respective blocks and give them a 2 tick delay (Right click them twice). Make sure they face the right way to make a circuit.

5.

Place Sticky Pistons above the protruding blocks so they face upwards.

6.

Place Glowstone on the Sticky Pistons.

You’re done! The Lever controls the on/off by completing the circuit and the Button puts a pulse into the circuit to start it. Now just decorate your exterior, you may want to use Black Wool on the insides so the Glowstone only shows when it pops up. :D

Item images:

www.minecraftwiki.net