A simple button is easy if it’s mains powered – – it’s just a momentary switch. The issue is when you want it to be battery powered and you want the battery to last more than a week or so.
Both Z wave and zigbee use the concept of “sleepy devices” for small battery powered things like buttons. The button sleeps much of the time and then only wakes up when you press it. The problem is that if the sleep time goes on for too long, it may have become disoriented and it may require a second press before it’s actually connected to the network and processes the button press.
This means different customers will have very different experiences. The people who use the button two or three times a day may be much happier with it than the people who only use it a couple of times a month, because those who use it less frequently may find that it keeps going to sleep. Because of this customer dissatisfaction, a lot of companies have been reluctant to go into it.
If you just want a very simple button that won’t have this issue, use a Wi-Fi button, but be prepared to replace the batteries every couple of months. You can get a dash button from Amazon for about five dollars and repurpose it for this if you want. There are project reports in the community on how to do it. But the battery is soldered in place and can’t be easily replaced, so you may have to get a whole new device every few months if you use it a lot.
There are quite a few “simple buttons” on the buttons FAQ list which will have much longer battery life, but which may have the falling asleep issue depending on how often you use them. So it’s a matter of personal preference.
If you build one yourself and you make it battery-powered, you’ll still run into one of these two issues. But it’s up to you. 