[Rasna]

From Low-Tech, p. 14:

Combination Gadget
Combination devices aren’t new: Australian aborigines made multipurpose woomeras (p. 75) that could function as digging sticks, fire drills, handles for stone chisels, and even percussion instruments! To create such items, follow these guidelines.

Cost and Weight
Starting with the costs and weights of the component gadgets:
• If all of the gadgets can be used at once, weight is that of the heaviest gadget plus 80% of the weight of the others (weight savings being due primarily to shared housing). Cost is that of the costliest gadget plus 80% of the cost of the others.
• If only one gadget works at a time, weight is that of the heaviest gadget plus 50% of the weight of the others (due to shared parts). Cost is that of the costliest gadget plus 50% of the cost of the others.
For weight calculations, use the gadgets’ empty weight, after subtracting any ammunition weight.
Cost calculations always come before cost factor. Combined equipment cost is the new base to which cost factors apply.

Legality Class
A combination gadget’s LC is that of the component with the lowest LC.

According to Pyramid Magazine 3/52 (pp. 12-13) this rule can apply also for the combination of Armour and Clothing: the clothing cover, being lighter than the proper armour, is at 80% of its cost and weight.
The question is: does this rule also apply o armour with layered construction (helmet with integrated liner, khazaghand made of two layers of mail)?