でできる / からできる

でできている says what something is made of. The object takes は, the material takes で, and the verb is できる in its ～ている form.

で or から

Use で when you can still see the material in the finished thing, and から when it has been turned into something else. The line is not strict, and で is also heard for a changed material.

できている, not できる

できている describes the object as it is now: the making is over, and this is the result. It does not mean "is being made". Plain できる is for the process, and states a general fact about what turns into what.

• × このかばんは革でできる → このかばんは革でできている

Usage notes

These go beyond describing an object.

Asking what it is made of

Ask with なん何で, or なん何から for a changed material.

With 作る

The same split holds with つくる作る, when you name the person or the place that makes it.