Sling bag for Mamiya RB67

Looking for something as compact as possible (which would inevitably limit RB67 outfit). Would like to stick in 2 lenses and a chimney magnifier.

What are you using for an outing with an RB67 outside of large photo back packs, and what you can fit into whatever it is your are using?

I went to a Lowe’s (a hardware/building supply company in the US) and bought an inexpensive bad made for carrying electric construction equipment such as saws, drills, etc. It has a harder, stronger bottom than a soft bag. Its only problem is that it’s rather heavy. I’ve used it about 15-years. It includes a shoulder strap. I carry a body, two or three lenses, plus film, meter, filters, etc.