If you want to do a quick design for 3D printing, Tinkercad is pretty easy to use. Although it was briefly in danger of going out of business, it was bought by AutoDesk who have made a lot of impro… ...

Offered by Autodesk, Tinkercad is a free online platform you can use to build and test out your Arduino circuits. This way, you can start learning even without the components on hand.

so tinkercad has circuit designand arduno now, a real arduino is $20, IDE is free, fritzing is free and does all the exact same layout stuff locally, you save your files and keep them forever.