Originally uploaded by Redstone_Will, and re-uploaded with his permission.

From his upload:

This is a calculator I've been developing for around a week, and then added some new stuff from time to time. It supports 4-bit addition, subtraction, multiplication, and simple division (which means it doesn't work from numbers higher than 10). It has two input screens, a function screen, equal sign display, negative display, and a 3 digit answer display. A flat UI is also included and presents the input screen as an empty display, until you enter numbers.

Extras Include:

3x3 piston door with a torch detector

Lounge within a fountain (with small water bridges)

Triple piston extender table that present to you a cookie when you enter (in the lounge)

A secret 1x2 door that leads you to an elevator that takes you outside the main room and to the actual Redstone.

Outside (through the elevator) there is a small picnic table, and there is a glass walkway for viewing the Redstone. (Note: there's a lot of Redstone).

Enjoy =)