Weekend App: 3D Print Cost Calculator

A 3D Printer has been on my shopping/wishlist for some time, and this Black Friday a very nice one came up for a very good price, I had always assumed that the running costs of such a thing were relatively high, quite happy to say I was very wrong on that one.

After a few weeks or mostly thumbsucking how much things cost I took to DuckDuckGo to see what calculators existed, and while there are quite a few, they were either very simple or overly complicated for my “for funzies” use case.

I was not running a business, so cleaning and polishing times were not factors, other staff did not exist, so the complex ones were a non-starter really and the simple ones to me did not give the whole picture, sure the filament in most cases is the bulk of the cost, but electricity is also a factor and I like full pictures.

To solve this “problem” I wrote a really simple app, initially, I was going to just spin up a spreadsheet, but those suck to use on a phone.

Spinning up an app also gave me the chance to play with more recent developments in the Flutter community.

The Very Good Venture CLI has been floating around my Twitter feed for some time, so when bootstrapping this App I went with that, and I must say I really do like the boilerplate they provide. It ships with BLoC as well as the VGV linting config as well as a nice GH Action script.

With that, I also added in form_bloc, which, considering the size of the app was complete overkill, but oftentimes trying out new things can be a lot easier in a very small and specific use case. With that, I was also quite impressed, forms in general suck and this does simplify it while also providing a few useful extras.

As mentioned, the app is really simple, it is just one screen and I had only planned on having it as a PWA, but after a day or so, seeing as I already had a developer account with Google, I figured why not…

You just scrolled past the screenshot, and that quite literally is all there is to it, the 6 input field and the result underneath, that is actually the 3rd “update”. The initial version had all the inputs with a “calculate” button, which then revealed the results.

After that, I decided to make my life easier and add in sembast which I really wish I had found sooner for another project, but anyway. This seemed about the easiest way to store data long term for the web so I persisted the top 4 fields, Printer Wattage, Electricity Cost, Filament weight and cost as those 4 are the least likely to change between calculations.

The last 2 will always need to be filled out, but the last/most recent update was to actually remove the calculate button and just run the math as the values are completed.

I still need to spend some time working on the testing, have not quite figured out how to correctly test form_bloc and I just need to sit down and do the widget testing, while this app is simple enough to arguably not need extensive testing, I quite enjoy the testing and it’s the small simple things that can sometimes teach you the most.

The problem you run into in the tiny 1-page app, could and will likely also crop up in the big 12k+ LOC project, and it’s probably not going to be easier to solve in that one…

For those interested, here are all the relevant links, you can play around with the app and even dig around what very little code there is…

I hope you found this interesting, and if you have any questions, comments, or improvements, feel free to drop a comment. Enjoy your Flutter development journey :D

If you liked it, a like would be awesome, and if you really liked it, a cup of coffee would be great.

Thanks for reading.

Originally published at https://remelehane.dev on December 28, 2021.

MTBer, Runner, Developer, Gamer. | Front end Architect at Wyzetalk with 10 years Front-End Experience & ~2yrs Flutter. | React Flutter Javascript