NOTE: Currently since 3Sixty version 1.1.1 you can easily use any image file as hotspot icon. Check out this blog post: https://3sixty.webappdev.my.id/2022/04/now-you-can-easily-use-any-image-file-as-custom-hotspot-icon-in-3sixty-web-tour-maker/
All the hotspot icons in 3Sixty are base 64 encoded images and they are stored in a file named imagedata.js. You can create your own hotspot icon by converting any image, for example a transparent png image to base 64 encoded image by using this cool website https://www.base64-image.de/ then copy the code and paste it inside imagedata.js file.
In this video I will let you know how to add a custom icon to your 3Sixty Web Tour Maker software to be used as a hotspot icon in your virtual tour.