It will depend on the designers of the aircraft.
Most vintage and American aircraft will be measured in inches. Where as more modern and European aircraft will use millimetres and the metric system.
The reason these units of measurement are quite small even on a large passenger aircraft like an Airbus A380 is that everything has a design sheet, commonly known as a blueprint. Each component, panel, window and part that goes up to make an aircraft is designed individually. These component parts are all then given a higher level of drawing that shows how the small parts make a larger part, then finally how the larger parts make the aircraft as a whole.
An example of this is there will be a design sheet for a wingtip navigation light, showing its dimensions. Then there will be a design sheet for the wing, showing where that navigation light fits onto the wing. Then finally a main drawing showing how the wing fits on the aircraft. This level of detail can go all the way down to a drawing for each screw that holds the navigation light lens onto the navigation light body.
But regarding of how small or large the item is, from a single screw to a whole aircraft, the drawings will all be in the same unit of measurement.
As a potato chip is light weight I would use grams and milligrams.
You would probably measure a keyboard in centimeters (cm).
A meter stick would be one. A metric tape measure would be another.A measuring tape.a rulerA meter stickyou can use a metric tape or a yardstick or a metre trundle wheel and finally a metre stickA tape measure, calibrated in meters.A meterstickusually a metric measuring tape.
Liters
What metric unit would you use to measure a computer keyboard
kilometre
You would use the metric unit "kilograms" to measure the weight of a bag of groceries.
You would use the metric unit "kilograms" to measure the weight of a sack of peaches.
A refrigerator would typically be measured in kilograms (kg) in terms of weight in the metric system.
Mass and weight are two different things: you cannot measure the mass of your weight. That is like talking about the temperature of your height - it makes no sense.
A gram would be an appropriate measure for its mass.
gram
You would most likely use milliters.
The weight of the box would be measured in grams.
A scale
Mass is measured in kilograms.
Every country in Europe uses the metric system, meaning they would measure weight in kilograms, grams, etc.