Not my work, can't take credit. Here is how the author created those: http://67ekjdzqxmmmuiv.codecalm.net/editor.html and all icons are created with a line, an arc and a circle. I found this repo linked on a polish website and figured this community can benefit from it. I also pinged the author to join and answer a few questions you guys have here.
From a UX experience, I think you'd be more successful if you would let the user experience everything your site has to offer and if they decide to continue (or stay with the site, save their prefs and eventually - become paying customers) - give them an option to create an account, because according to the latest research in UX, any login walls (even the FREE account ones) are detrimental. Check the article I linked above.