How can you measure irregular objects?

do you mean getting the area???

For Area:

Place the irregular objects on a graph paper and trace the outline of the object. Now count the complete square as 1 and other incomplete as 0.5 or so according to how much it occupies. Now finally sum them up and that would be the area of that particular object.

If you mean to say volume then:

You can find the volume of an irregular object by the displacement of water. In order to find the volume by displacement you need a measuring cylinder.

In the measuring cylinder pour some water in it up to a certain point such that you can read it. Now insert the irregular object in to the cylinder gently. Now read the height of water on the cylinder. Now deduct the first reading from second, that should be your volume of irregular object.

If finding perimeter then

trace out the outline of the object and simply measure the length of the object on the paper.

** Note: you must trace all side that you can see