Probably better to watch the video, but here's a written guide:
1. Load up the mission Perimeter Wall in the IPSILON campaign.
2. I build a machine with a ton of wooden logs/cannons to be used as debris to hit the buildings.
3. I put some bombs on the back side and bottom at the back. Too many and you'll see the debris shoot too far.
4. Make sure the machine is still up in the air, start, and let it drop.
5. The debris/parts will shoot up and forward, sometimes hitting the walls.
*It is very hit or miss, not super reliable. However, if you catch a building on fire. LET it burn, and it'll count.*
*Note: This is the harder Rube Goldberg achievement. The other one is easier*