3DPrinting

ive done this research for a project and this is what i found:

Clear resin can be transparent, but “perfectly glass-like” out of the printer is a myth. Here’s what you should expect:

Raw Print Clarity

• Most SLA/DLP clear resins come out looking cloudy or frosted. Layer lines scatter light, and the cured surface tends to have a slight haze.
• Even high-end resins that advertise “water clear” need careful handling—straight off the printer they’re closer to frosted acrylic than window glass.

Post-Processing is Everything

• Sanding & Polishing: If you sand through grits (400 → 3000) and then buff/polish, you can achieve near-crystal clarity, especially on flat faces.
• Clear Coating: Spraying or dipping in clear acrylic or epoxy can restore transparency and give a smooth finish without hours of polishing.
• UV Over-curing: Too much UV exposure yellows resin and makes it cloudy. You’ll want just enough to finish curing.
• Surface Orientation: The side that prints directly against a smooth FEP or a glass plate can come out very clear—almost lens-like—while support-touching surfaces will be rough and need finishing.

Practical Reality for Your Project

If you sandwich a printed photo between two unpolished clear resin halves, the picture will likely look murky, as if behind frosted glass. If you’re willing to polish the inner faces, you’ll get a much cleaner look—but alignment and dust control will be tricky.

For something like keychains, most makers actually skip the “clear 3D print” route and:

• Use UV-curable dome resin (like jewelry makers use) poured into bezels or molds. Much easier to get crystal clear and bubble-free.
• Or laser-cut acrylic, which is optically clear and needs no polishing. You can sandwich artwork between two acrylic pieces and bond with clear adhesive.

Recommendation

Resin 3D printing can work, but only if you’re ready for a lot of sanding, polishing, and sealing. If your main goal is crisp visibility of the artwork, poured resin or acrylic sheets will get you there faster and with more reliable clarity. The printer route shines more when you want unusual shapes or embedded 3D geometry.

The gear on the right is fairly typical of how it looks coming out of the printer. You can clean up the frosted glass effect with a bit of polishing, but it isn't ever as clear as the part in the middle.

However, everything I've used starts to turn yellow very quickly. Maybe there's new stuff, but I've tried various lacquers and clear varnish but it all turns yellow in a few days.

It is really difficult to get consistent optical properties using additive manufacturing techniques. There's a reason optics (lenses, etc) are basically universally made from uniform pieces ground down and polished smooth, and compound lenses are avoided unless absolutely necessary and to make them optically clear enough requires exceptionally complex and expensive methods. With typical additive manufacturing, you are making something that is basically hundreds or thousands of compound lenses stacked onto each other, and the optics are always going to be pretty awful no matter how much care you put into the process. There is no easy answer, except to not use additive manufacturing for this. For optical properties, you really want to stick to a single shot of consistent material as much as possible, to minimize internal refraction (which happens at every material surface transition if it's not perfect, which it won't be). Cutting material away is fine, you're getting rid of the old surface transition and creating a new one, you always have to interface with the outside air at some point, and that's the minimum number of refraction layers you're going to get. Adding material to it creates another layer of internal refraction for the light, making many of those is very not good.

While there are people working hard to make additive manufacturing methods that can do this as well as possible, and in a few cases they've gotten quite impressively good at it, they're still starting from a compromised beginning, the deck is stacked against them and it really is a challenge. If at all possible, don't use additive manufacturing for this. It's the wrong process for the job. The traditional approaches of molding or cutting or machining or polishing to create the shape you want, is the right way to do it. If you really need something unique you may have few good choices, but if you can get something off the shelf, it'll save you a world of headache. This is only something worth doing for the challenge of it, and you should go in with the expectation of failure, and prepared for joy if you succeed, and I'll be happy to know that you've proven me wrong.

It can be clear like the formlabs sample, but its not clear like molded acrylic or acrylic sheet. It has some cloudyiness to it.

You can buy the keychain halves from all express, or epoxy molds.

Before you go too far down the 3D printed resin route, look and see if laser cut acrylic might work for your needs. There are services where you upload a vector file, and they’ll cut out a piece of clear plastic with whatever shape and thickness you need. At that point you just need to sandwich the pieces together and apply some fasteners.

If you’re just sandwiching flat paper between two layers then why not just laser cut the clear layers? Wouldn’t have to deal with the UV yellowing of the resin in that case.

Not terribly clear off the printer but I've seen people dip them in something. Can't seem to remember what it is. Epoxy, maybe? And that makes them super clear. You could probably also just hit them with a clear coat from a spray paint can.

Even then, it's susceptible to absorbing oils from your hands, and being damaged by UV, both which will turn them yellow after a while, like all clear plastics (other than acrylic).

I posted this a while back, came across a post on hackaday on doing clear lens on a resin printer with lower effort, the article links an older one about doing clear resin prints that might be helpful. To me they look pretty decent, certainly a heck of a lot better than any transparent prints I've done with a filament printer.

As others said though, easiest would probably be doing something like laser cut acrylic and sandwiching the picture between them.