The infamous "Chalkley Cup" that Harv refers to has proven to be a pretty good solution to carrying liquid refreshments on the tractors. It stays where you put it and doesn't move around when in motion.
As far as carrying small tools, gloves, extra pins, etc., I have a
B7100 and thought about several different solutions. I ended up with a tool bag purchased at Home Depot that hangs from a "J" bolt secured to the ROPS with two hose clamps. There is a photo of the bag, j-bolt, and ROPS in the tractor photos forum under "
B7100 Tool Bag". It carries a variety of small hand tools, gloves, flashlight, etc., etc., etc. and seems to be working just fine. Even with all the hours the past week in the cold and snow here in SE Michigan pushing snow around, the zippers haven't frozen.
I would guess the
B7300 has a lot of the same space constraints the
B7100 does, so you may want to look at these solutions. Good luck.
Bob Pence