Wanted to automate payroll. Needed to be as simple/easy on the eyes as possible for your run of the mill user.

General functionality is that it makes digital timecards for every employee action/swipe of an RFID tag. Every swipe also punches a Google Sheet based on company department, by utilizing regex to find column associated with employee name, then the row based on today's date. It then punches current military time to corresponding clock in/out offset. The timecard math is all done using the Google spreadsheet functions to discern overtime, total hours, etc... More will be included later to automate even the spreadsheet template even though copy/pasting once every 15 days is trivial.

It's comprised of a OPi-Zero, MFRC522 RFID Module (for employee badges) a modified case, multi LED for clock in/out prompting, Google Sheet API and several existing dependencies/repos on GitHub. The most important 'juicy', details are documented on GitHub which will get you installed and running with the API, Module, LED, etc.... With more details to come, including step by step instructions on setting up Google Sheet API, etc.... Let me know what the community thinks.

https://github.com/BiTinerary/TimeClockPi

Installation >> Connect MFRC522 Module and run >> git clone https://github.com/BiTinerary/TimeClockPi && bash ./TimeClockPi/requirements.sh

Hmm, if it is just to collect time-stamps okay.

But in daily life with a couple employees you better go for a professional solution - it is terribly complicated.

Welp. It currently works for...more than a couple employees and has been tested using various means/devices for months.

I could go into more detail but your opinion does not apply to my specific circumstance. Regardless, thanks for the criticism. (seriously)

In my experience every 'small business' solution to this has been to simply, not have a time clock. Again, I could go into details but I'm not the trend that every local business owner I've met, has set.

I don't know what you mean by terribly complicated but I beg to differ. Let OPiZ offer RFID interface to a Gsheet. Let Gsheet functions calculate all the math.
This solution in tandem with a 'profession' timeclock that costs several hundred not $25 dollars, to create a physical timecard that needs to be digitized later, produces (dare I say) foolproof results.

What I mean. People forget to stamp, work partime, work partial partime (accident)  just to name a few. If you are a mathematician no problems, but it is a problem for Excel beginners.

I got a couple years back their product (may be Google Translate can help) you can stamp on PC and with RFID also keep track of vacation. Of course you pay an initial fee, and for support.

This is what I wanted to express.

Yea I get that. Totally understandable. In some situations, especially bigger companies, you would want to go with a more professional solution like you describe.
Of course people forget to stamp, isn't that going to be an issue regardless of the device though? I don't think you need to be a mathematician, to do a timeclock. Let a spreadsheet do that for you. 

All that aside, as a whole SBC's represent (to me) the option and freedom to do without those kinds of proprietary (usually expensive) devices that offer zero control. On top of doing without the service fees and support. At the end of the day everyone (company) is different. This solution works excellently for my situation.

Another good situation I've been in previously, was working for a fairly large company (as in multiple local locations) that had hours averaging 1, maybe 2, employees per location. I imagine it would be cost prohibitive to buy 6-7 devices, for a grand total of 8 employees. Granted, some of these positions were salary and timecards were based on the honor system but I could see an SBC making an appearance here.