How to create a horizontal support beam

I’m fairly new to the software, but have been building out our vacation home (currently being built in real life) so I can visualize things and help decide how the kitchen should be laid out. I can’t find any generic shapes or even beams to use for a support beam I need to put up.
Since nothing needs to be structurally accurate, I have sometimes repurposed a cabinet to make low partitions, and that looks fine. But for a beam, the cabinets have no bottom, so that trick won’t work.
What is the best way to do this?

If your asking why I’m not using walls for a partition. It kept connecting with an existing wall and closing off a large opening in the wall that leads to a lower level (not another floor, but a lower level. I’m sure there was a way to do it correctly, but I got frustrated.

I’m attaching my version using a stretched out cabinet as the beam so you can get an idea of what i’m trying to do.