Piecemeal Armor

What happens when a character takes a heavy metal breastplate from a set of full plate and then wears studded leather sleeves, and padded leggings? (That is, what happens other than he looks stupid?)
Characters can wear armor assembled out of the remnants of other, mismatched sets of armor. It's not as good, and certainly not as good-looking, as wearing a matched suit. But sometimes necessity dictates that characters wear what's on hand.
When you're assembling a full suit of armor out of pieces on hand, the first thing to do is to see what you have. Compare your armor on hand with the chart below, rounding halves down in the final calculation, and three quarters up.

Bonus to AC Per Type of Piece	
Armor Type	Full Suit	Breast Plate	Two Arms	One Arm	Two Legs	One Leg	
Light armor							
Padded	+1	+1/2	+1/4	0	+1/4	0	
Leather	+2	+1	+1/2	+1/4	+1/2	+1/4	
Studded lthr.	+3	+2	+1/2	+1/4	+1/2	+1/4	
Med. armor							
Hide	+3	+2	+1/2	+1/4	+1/2	+1/4	
Scale mail	+4	+3	+1/2	+1/4	+1/2	+1/4	
Chain mail	+5	+4	+1/2	+1/4	+1/2	+1/4	
Heavy armor							
Splint mail	+6	+4	+1	+1/2	+1	+1/2	
Banded Mail	+6	+4	+1	+1/2	+1	+1/2	
Half plate	+7	+5	+1	+1/2	+1	+1/2	
Full plate	+8	+5	+1 1/2	+3/4	+ 1 1/2	+3/4	

Example: A character is robbed of all his worldly goods. Later, he finds the aftermath of a battle, with a couple of dead warriors still in their armor. He manages to scavenge a breastplate from a suit of half plate, a decent chainmail sleeve, and a pair of studded leather pants.
He tries to piece this together into a suit for him. The breastplate grants an AC bonus of +5. The single chainmail sleeve grants a bonus of +1/4. The pair of studded leather pants grant an AC bonus of + 1/2.
His AC is now is +5 3/4 (rounded up to +6)—not too bad. If there's a shield, he'll have an AC of +7, and if he can salvage a helmet, his head will be protected from specific strikes. Now if only he could find protection for that vulnerable single arm...

Weight of Piecemeal Suits
To calculate the weight of a piecemeal suit of armor, follow these guidelines:
•	The breastplate is 60% the weight of the original suit.
•	Each arm and leg is 10% the weight of the original suit.
In the example above, the cobbled together armor would weigh 38 lbs. (30 lbs. for the breastplate, 4 lbs. for the chainmail sleeve, and 4 lbs. for the pair of studded leather leggings).

IMPAIRMENT OF PIECEMEAL SUITS
Unfortunately, piecemeal suits of armor tend to encumber their wearers more so than properly-tailored full suits of armor do, for obvious reasons. To find out how much a piecemeal suit encumbers a character, and how it penalizes their dexterity, inhibits their dexterity bonus, and interferes with arcane spellcasting, do the following:
Locate the full suit of armor with the weight closest to, but heavier than, the piecemeal suit, and reduce the Maximum Dex Bonus by 2, increase the Armor Check Penalty by 2 (making it worse), and increase the chance of Arcane Spell Failure by 10%. Use the modified Speeds normally. In cases where more than a single full suit is comparable in weight, use the one with the worst penalties.
Continuing our previous example, we find that the full suit of armor with the weight closest to the piecemeal suit (38 lbs.) is Chainmail (40 lbs., Max Dex: +2, Armor Check: -5, Arcane Failure: 30%). Using the Chainmail modifiers as our basis we get Max Dex: +0, Armor Check: -7, Arcane Failure: 40% for our AC +6, 38 lb. piecemeal suit.

About Magical Armor
If a suit of magical armor is used for one of these piecemeal efforts, it grants none of its magical bonus; once the magical armor is split into little bits, or pieces are merely separated and not worn together, the magical bonus doesn't work.