How to make custom size of FloatingActionButton

Because I don't use FAB of mini size, I redefined this size.

dimens.xml:

<resources>
    <dimen name="design_fab_size_mini">100dp</dimen>
</resources>

layout.xml (first FAB will be bigger than second one):

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/addPhoto"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        app:fabSize="mini"
        android:layout_marginBottom="@dimen/fab_margin_bottom"
        android:layout_marginRight="@dimen/fab_margin_right"
        android:src="@drawable/ic_photo_camera_white_24dp"

        />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/addPicture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:layout_alignParentBottom="true"
        android:layout_toLeftOf="@id/addPhoto"
        android:layout_marginBottom="@dimen/fab_margin_bottom"
        android:layout_marginRight="0dp"
        android:src="@drawable/ic_photo_white_24dp"
        />

Since support library 27.1.0 there is an attribute for this:

Just set app:fabCustomSize