I just started thinking about this because in a GDFB catalog they have a helmet, it looks similar to a Medieval Armet, though they call it "European closed helm 17th century".
I can't find a picture of it online since I think it's been discontinued, though does anyone here have any photo examples of plate armour from the 17th century or later?
By plate armour I mean a "traditional" full harness, not just a cavalaryman's breastplate. A few websites mentioned full plate being used up until the early 18th century, though of course they don't show any examples.
Does anyone here maybe have an example from a museum or something?
Thanks! :)

There are tons of 17th century harnesses extant - just search for "cuirassier armour". Search on Flickr. Todd Hoogerland has lots of great photos from museums. Here.

Lots of armour from the Thirty Years War era. Germany, Netherlands, France, Italy - all used it. Both burgonets and close helmets were worn, though not armets. By the English Civil War, full armour was very rare, though still occasionally used. Arthur Haselrig fielded a regiment of horse in full plate, during this war. Even after armour had become impractical in battle, very rich people and royalty often had armour made for them (because they could.) Armoured cuirassiers could be an effective shock troop, charging in with swords and pistols to break up and rout infantry. The armour could withstand a pistol ball, though muskets at that point were powerful enough to destroy it. You'll often see "proof marks", bullet dents in the breastplate - these were done by the armourer to "prove" that the steel could hold up to gunfire in battle. (A study by David Edge found that they were usually proofed with underpowered loads.)

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Usually there were no greaves or sabotons - very heavy leather riding boots would be worn instead. But some of the armours made for really rich nobles or royalty in the 1600s did have full leg protection. Louis XIII wore this nice armour around 1630:

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His son Louis XIV owned this armour:

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The pauldrons were usually square rather than rounded. Some Swiss armours had fanned out lames in the pauldrons.

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Oh, thanks for the photographs and the link!
Some of those are quite interesting. For some reason I had seen that style of armour before, though I just remembered it when I saw your post!

This may be off topic but something always riddled me about those harnesses.

How did they carry their swords?
Was this style of leg protection practical is one had to dismount during a fight and continue on foot (horse gets killed etc.)?

I came across this early 17th century full armour in the Royal Armouries a few years ago:

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Well Wertheim describes how a regiment of Cuirassiers raised by the Elector of Cologne discarded all or their armour except for the helmets (and possibly the gauntlets, my memory is a bit hazy) making these expensive soldiers "worse than harquebusiers"

Much depended of how strictly the officers of a regiment and/or company enforced the regulations. In theory the losing of equipment could be severly punished, particularly in armies such as the Swedish were a significant part of the armour belonged to the Crown.
Veteran soldiers were very aware of the important protection the cuisses provided, Basta considered them essential because so many blows struck the thighs, including the "the shot of pistols which are deadly".

So wether armour was discarded or not depended on many factors. Overconfidence could certainly lead to troops doing stupid things. Swedish cavalry in the early 1600's had gotten used to not need their armour when fighting the Russians, several veteran officers scoffed at the idea of puting on harness to fight the Poles only to get themselves and their men killed and/or routed when they had to face Polish & Lithuanian lances.