I hadn't heard of the Harvey's Casino bombing until it was covered recently by the Sword and Scale podcast, but I found it to be a really interesting story. Long story short, John Birges:

...took exception to the amount of money that he'd gambled away at the casino over the years, and in 1980 tried to extort $3 million out of them with a bomb threat. But rather than cut corners, he spent months designing and building one of the most complex bombs ever created. He disguised it as computer equipment and wheeled it into the casino under an "IBM" cover, leaving it in an office with a ransom letter sitting on top, to be later discovered by a security guard doing his rounds. As described by Adam Higginbotham on Sword and Scale,

"...the initial security guard then called the head of security, this guy named Simon Kaban, who in the weeks previously had been on a letter-bomb training course...when he caught sight of the envelope, he didn't pay so much attention to the huge bomb that he could see sitting directly in front of him, but was fixated on the envelope. So he and another security guard got hold of two broomsticks...and they leaned on the bomb and began poking very gingerly and carefully at this envelope that they could see on the floor, fearing that they were dealing with a letter bomb....Kaban is leaning on the big box, when the other security guard looks up at him and says, "That", pointing at the big box he's leaning on, "...is a bomb", at which point Kaban and the other security guard gently lift their weight off the device and back away."

The bomb, from the outside, looked like this:

The only visible interface was a collection of 28 toggle switches, with number 23 switched on; the rest of the device was sealed. Inside the bomb was more than 800lb of TNT that Birges had stolen from construction sites, in addition to EIGHT independent trigger systems:

After X-raying the device, the bomb squad decided to attempt to explosively separate the top and bottom sections, believing that the TNT was all contained within the larger bottom box, using shaped C4 that would potentially sever any electrical connections before a signal could travel to the explosives below:

It didn't go so well (the top section had also contained a small amount of dynamite, which detonated the larger bottom box).

Birges was eventually caught when his complex plans for collecting the ransom money fell through. Today, the FBI still use a replica of Birges' bomb as a training device for their agents.

Well done that man (in an evil mastermind kind of way). Nobody was hurt after all.