Version: 2.4.2 What is the bug: Any block that maintains inventory/fluid/power on breaking can be used in conjunction with the Drawbridge for massive dupe potential. Mod & Version: Tinker's Mechworks since 1.6.4 Paste.feed-the-beast.com log: Can it be repeated: Yes. I'll example using the Immersive Engineering Crate. Acquire ImmEng Crate and a Tinker's Mechworks Drawbridge. Place Crate on ground and place one iron ingot inside. Break Crate. Place Drawbridge on the ground and place Crate inside as the block to be extended. Apply Redstone signal to Drawbridge, extending the Crate. Remove iron from Crate. Stop Redstone signal to Drawbridge, retracting the Crate. Reapply Redstone signal to Drawbridge, extending the Crate again. Remove iron from Crate. Rinse and repeat. Known Fix: Add any block that maintains inventory/fluid/power on breaking to the Drawbridge blacklist in the configs.