itch.io

Yes. Just to be clear, if you make an instance of the EggTimer contraption and edit it's script, it will have a template like

on finish do
end

You can then fill in an event handler for "finish" like you would any script. For example,

on finish do
 go["someCardName"]
end

Note that if the only thing you want to do is wait 10 seconds after clicking a button before navigating to another card you could use the sleep[] function on an ordinary button's script:

on click do
 sleep[10 * 60]
 go["someCardName"]
end

The difference being that sleep[] is "synchronous" and prevents the user from doing anything else while the script sleeps, whereas the EggTimer is "asynchronous" and the user could click something else or navigate away from the timer before it goes off.

The attribute exposed externally is `seconds`. The internal accessor/mutator functions are therefore named `get_seconds` and `set_seconds`, respectively. From the outside, you can modify the attribute like

eggtimer1.seconds:180

If you just want a timer and it doesn't need to be this "egg timer" specifically.... 

Making timers from scratch comes up from time to time, and it's pretty easy. 

Here's a small example in the programming questions thread that would start automatically when the card is viewed. 

And here's another thread talking about making timers.

If that seems like something that would work as a replacement for what you wanted the EggTimer Contraption for, then I'm very sure folks around here would be happy to answer questions to make sure your home made timer does what you want it to do.