for bigger horns make the base shape using tinfoil then cover with air dry clay or polymer if u have an oven and aren't broke like me. just smoothen it then paint then seal like normal biz

there's actually an official cosplay resource on homestuck.net, there's stuff from props to godtier outfits im pretty sure. and you can always search on tumblr theres tons that's where i usually look for

https://homestuck.net/resources/cosplay.html