Actually, a lightsabre-like device is almost possible using technology that exists in the early 2000s. Hot plasma delivered through holes in a telescoping tube ordinarily stored in the sabre's handle would produce a column of superheated glowing gas capable of cutting through steel. There are similar devices at work right now in heavy industry, the only problem would be finding a power source compact enough to be handheld.
Incredibly bored/nerdy threadjack :c
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Sorry.