Just showing off some trial-and-error mods I did with my cupholders.
Most mornings I have a 16-oz stainless steel coffee mug, tall with a half-hourglass or inverted-coke-bottle shape. (Sorry no pic of it.) Because the bottom is narrower than the top, it tends to tip over, though it hasn't done so to the point of spilling. But it is a bit disconcerting when making that first left turn out of the sub.
I added some thick foam rubber on one side, another piece on another side, to try to "crowd" my mug into place to keep it from tipping over or banging around. I added some felt pads to the third side to reduce rattle or banging noise.
Most mornings I have a 16-oz stainless steel coffee mug, tall with a half-hourglass or inverted-coke-bottle shape. (Sorry no pic of it.) Because the bottom is narrower than the top, it tends to tip over, though it hasn't done so to the point of spilling. But it is a bit disconcerting when making that first left turn out of the sub.
I added some thick foam rubber on one side, another piece on another side, to try to "crowd" my mug into place to keep it from tipping over or banging around. I added some felt pads to the third side to reduce rattle or banging noise.