My mom has a hole in the ground that she puts her clothes drying hanger in. Like this. The hole in the ground is a 2" or so pipe, set in concrete. The pipe has filled with gravel. Anyone have a tip on getting the rocks out? I can only get so many out using my fingers and then trying to use a set of chopsticks.
I used to live in a house where the gas shutoff valve for the fireplace was in the living room floor, controlled with a little key. It was the perfect size for a marble to fall in and block it.
I found a metal straw and taped it to the end of my vacuum hand attachment, effectively forcing the suction through the straw. I felt I may have been straining the vacuum a bit, but I was able to pull the marble out easy-peasy.
If you have an attachment that fits in that hole, you’re good. If not, you can use a similar method to this.
If the shop vac can't get down far enough, duct tape a bit of PVC pipe or some other study tubing to the end of the vacuum hose. The standard nozzle might be too short or wide for getting where you need it, but it should be the quickest way to do what you need.
It is practical as rocks should float in mercury and it is safe if you use elemental mercury and don't eat it.
It isn't environmentally fantastic and you would want to remove it with a vacuum trap, which does make it a less than ideal option compared to a shopvac.
If OP is in the US -- which I assume he is, from the inch measurement -- I'd bet that he can probably rent one at a large hardware store, like Home Depot, if he doesn't have any use for one outside of this.
Something like this might work. They are kind of expensive, and some are better made than others, but they come in handy and maybe you could borrow one from somebody. A landscaping company might have something like this too that they use to get fruit off of trees, or maybe a fire department has something like it. Possibly a pond and aquarium store has some equipment that could work since they need nets and tools for plants and rocks, or tools used for feeding aquarium animals and fish. There are some home improvement stores that let you borrow tools or rent tools, shop vacs, long handled gutter cleaners or painting tools etc.
Vive Suction Cup Grabber Reacher 32" (2 Pack) - Elderly Grab It Reaching Pickup Tool Heavy Duty for Seniors - Trash, Sticks, Litter Picker Upper - Extra Long Reach Handle & Handy Extension Arm Claw