Not only are microSIMs senseless, but when swapping SIM cards while walking today and so had to hold a SIM for a moment with my lips, as I had phones and batteries in both hands, I realized the choking hazard which microSIMs pose! They are actually dangerous!

At least if ordered online Fonic now automatically deliver microSIMs, which come in a carrier card so you can also use it in regular SIM-slots of course. Unfortunately they deliver only to German addresses and a German bank account including a mandatory initial recharge of € 10 is required for online purchases.

Cutters and adapters available
 

On Amazon, you can buy cutters to cut the larger SIM cards down, and adapters to make the smaller cards fit into the larger slots. I think that you can probably cut with scissors, too, but the cutter might make it easier.