As of today Gumroad no longer allow the sale of NSFW content, including 3D models.
They do this because they need to please the payment gods, Paypal and Stripe.

Because of that I will therefore be having a 100% off sale on everything, for as long as they let me.

Simply go to my Gumroad page : https://doublestuffed.gumroad.com/

Then use this code : FUCKGUMROAD