Resin for Props

What kind of Resin should i use to make strong and durable props? I’m trying to make helmets, like the ones from the movies, and I want something that is strong and durable and could feel like ti is from those movies. Which resin should I use to get those results?

Durable and Though are the way to go. Tough is a but more prone to breaking under high impact but is also more rigid which can be an advantage if you want to put a strap on the helmets or by any other means put the part under constant stress.

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What about the grey pro or the rigid resins, how do they compare to the tough or the durable resins?

With grey pro it’s difficult to say because Formlabs is trying to sell it as a better Grey resin for engineering purposes but hasn’t been able to demonstrate in practice how it’s better (the mechanical properties supplied show the resin is a tiny bit better than Grey in some area, yet more brittle, and we have no more information than that)… supposedly the main advantage is that it’s more optimized for constant-load application which is a use case I haven’t had any issues with when using the standard Grey resin so really, I don’t know what to think.

Rigid is IMHO overkill for your application. Hard doesn’t mean durable. It usually means more brittle, which is something Rigid is trying to alleviate, yet it is still not as durable as Tough or Durable for you application I think.

That being said, I haven’t yet tried Rigid or Grey Pro, so my comment is solely based on the TDS and Formlab’s words on the forums and advertising material.

I’ve used grey pro and rigid quite a bit for engineering R&D. I love these new resins for my uses. But for prop making like you’re looking to do, I’d still recommend tough or durable. I’d start with tough, as it gets pretty strong once post cured.

For a helmet this type of printer would not really be a great idea–reason is that it’s designed for high detail but the maximum part size is not that big (though it’s pretty big for an SLA printer).
You might want to look into an FDM printer which can produce larger parts with much cheaper material. If you have some detail parts you can mix the two printing types or have the detail parts printed with a service.

For movie props wouldn’t you thing the surface quality of even a fine FDM printer is too poor ? Closeups on helmets in 4K will show every single detail.

I agree that SLA isn’t the most suited technique but there are none that come close in terms of surface finish without extensive post-treatment.

Would it be possible to elaborate on the uses you had out of Grey Pro ? Why would you use it in place of Std Grey ?

You’d have to sand it either way. The big deal with the SLA parts is that for something that big you would not be able to fit parts in the printer and you’d have to split them up. You’d have to fill in seams and sand things down anyway. On larger sized stuff the sanding isn’t a huge problem since there’s rarely much detail to have to work around. For smaller detail parts you can possibly get away with not sanding an SLA part, but there’s still some surface roughness with SLA due to the Z layers and with how the layers will not always perfectly align.
FDM printers are probably used a lot for full-sized props in movies these days due to the ability to make large objects quickly and cheaply.

i am thinking you are talking about making Actual size helmets for cosplay?

In which case none of the resins for the Form 2 are appropriate. They are costly. and the Form 2 would have to print them in a bunch of parts… its just not large enough.

If you are going human head size, then the best alternative is to vacuum form the helmets in just a few parts in an ABS or polypropylene. You can even vacuum form optically clear parts in PETG- vacuum forming is ridiculously affordable. And if you can’t find a vacuum former nearby- you can build one pretty cheaply.

If you are talking smaller scale helmets, close to the build volume of the Form 2 then your best bet is the durable resin… or maybe the tough… the Tough will be slightly more dimensionally accurate.

In my experience, grey pro is like grey but better. It’s stronger. It’s stiffer. It’s just as sharp. It just feels like a better formulated resin all around.

Is it still strong after 1 year exposed to ambiant light ?

I’ve only been using Grey Pro for a few months, so I don’t have much insight here. Our customer service team may have a better answer if you submit a ticket.

I used tough resin a few years ago to make curtain tie back hooks for my apartment. They get a lot of light and still seem to retain their original properties.

I have received a sample clip in Tough resin from Formlabs. It was flexible and after only 3 months, it breaked easily.

Tough does have some flexibility to it, but I am surprised to hear that your part broke after a few months. Usually the resin is quite impact resistant.

It is somewhat impact resistant but I had properly cured parts in the Form Cure, of reasonable size (say a rounded box of 50x50x100mm, 3mm wall thickness), break when dropped on a vinyl floor from a 70cm tabletop. These were properly designed injection molded parts that we printed for a functional prototype. I wouldn’t say that I am surprised to read that parts break “easily” especially if one if used to ABS/PBT/ABS-PC/PA6 parts.

That being said, Tough is an incredible resin and we use it very often. One just have to know the limits of the materials he is working with.