I've got a lot of small 1x1 gridfinity compatible things, like the Gridfinity soldering fingers. I don't really like to mount them horizontally, as they take up a lot of space, that could be used for other things that do better in the gridfinity system. However, I do have a big skadis board with lots of space.

I recommend installing standard Gridfinity magnets in the bottom of this, and using a bit of glue. You don't have to glue them in, the pockets are deep enough, and pressed up against a skadis board your magnets wont move, but it gives me peace of mind. I used hot glue.

This makes use of the Skadis T-Nut system. You will need 1 M2.5x12 screw, and 1M2.5 nut.