If I group an oven with the box I create, can I export it and use in my furniture library for later use?

The easyest way is to do this in a new and empty file. Place your lower cabinet, put your oven on top of it and create the frame if you need it.
And on top of the oven you can put e.g. a upper cabinet and adjust its height so it fits between the oven and the ceiling.
For easiest positioning set x ...

DIY! make a frame for the oven (with boxes)

I understood the explanation except for the part above.
How do I do that?

Hi

I am looking for built-in cabinet for my kitchen and I searched so many but I cannot find one.
A tall cabinet that has an oven built in.
Any ideas?