First up, having a kid is not good for your project blog life. Good thing it is just a hobby and not a source of revenue! I got this one done during a few nap times.
I use these little 3 and 5oz dixie cups a lot around the shop. Uses include: holding screws/parts, mixing paints and epoxies, holding glue, filling and funneling stuff, etc. A lot of the time there are pop-sickle sticks and acid brushes sticking out of the cups, and they fall over. I was trying to paint 3d printer resin (cool post coming, eventually, about this) and my cup kept falling over. I finished my resin job and got to measuring the cups and making a solution.
The cups are different enough that each required its own holder. One turned out to be snugger than the other, but they both fit well enough to prevent tipping. I probably could have left it there, but went the extra mile. I printed two sets of each with no infill. I used the slicer to make a hole in the bottom to allow filling the hollow cavity.
I always keep a big bucket of sand around for filling objects to make them heavier and damp vibrations. These all got a fill of sand until there was only a small bit of space left. Next I mixed up a little slow cure epoxy and injected just enough to flow out of the hole. I wiped the entrance, tapped the hole with painters tape, then let them cure upright.
With the epoxy cured they make for really stable dependable holders. Next time I do one of these I will try one of the open infill patterns like gyroid. The gaps might be big enough for the sand to trickle through and infiltrate all the infill areas. It will likely take a lot of shaking, but it would make for a lot stronger part. Using pure epoxy would be easier, but the sand is such a cheap way to weight things like this down.