I have seen a lot of people unhappy with the tension of the spring for the extruder of the Ender 3.  Some users stretch the spring, but I like this technique instead. Simply print the adapter, remove the spring, then choose whether you want to add .5 or 1 mm. Real simple and easy to change if you do not like your results. Per request... 1.5 and 2mm version added. =)https://youtu.be/7sDYr-5vIVg
If you have not snagged a Ender 3 yet, you can use this link. It is currently 169.99. If I get a coupon code I will add it as well.https://www.gearbest.com/3d-printers-3d-printer-kits/pp_1845899.html?wid=1433363&lkid=37680996
I get an affiliate bonus, you get a sweet printer that is one of the most solid in my stable.