They may be using something like Sift for security checking and something of yours was flagged. Source: over 1 year ago

But sorry to break it to you, this has been done at a really large scale already although most consumers are not aware. One big player here is https://sift.com/ Almost every major retailer uses their service exactly for the reasons you mention. Source: almost 3 years ago

Reddit, for one. A pretty big list on their homepage. Source: almost 3 years ago

If you already have the idea for the artwork, starting out on your laptop can do the trick, if it's more on the technical side like you want to draw something, an IPad will help big-time. You can try our Design Tool at UPrinting.com . Source: 6 months ago

I just had it made at uprinting.com As long as you are not selling them it is fine. If the Indiestone started selling them I would buy it from them. Source: about 1 year ago

I'm using uprinting.com They're physically close to me on the west coast and they'll do custom sizing so those were the primary selling point for me. Source: almost 2 years ago

You could do something like I did for alot of my maps. I got them printed on vinyl banners (also makes it easy with wet/dry erase markers). Places like Fedex/Kinkos (yeah kinkos is still a thing but it's been combined with fedex) could do it but they usually have to "send it out". So I would just recommend places like vistaprint.com, uprinting.com (where I got mine), esigns.com , bannersonthecheap.com, now if you... Source: almost 3 years ago

Uprinting.com should do what you're asking I think. Source: about 3 years ago