I see the problems you hinted at in this case. But there are a variety of 3D manufacturing technologies with different materials. And 3D printing is used in índustrial final-product production meanwhile. Even for components for aircraft turbines. In same cases 3D printing is the only way to make that part, in other cases it is the most economic.
Whether this technology can be a manufacturing alternative at the moment for our fim holders I am not sure, as it should end in a part made of ABS or similar, with high dimensional quality and good surface finish. But technolgy is close to it at least.
But they also could be produced in conventional ways other than moulding.
Also could 3D printing be combined with conventional means.
Where 3D printing is used as a primary production method the cost of doing so is fantastic, more than would be tolerated with consumer production, and that cost is tolerated only because 3D printing is really the only practical way to manufacture those parts. I remember hearing that the US military was using 3D printing as part of the manufacturing process of some of their drones because the small quantity being built would have made any tooling for more conventional methods too expensive. I will agree that 3D printing allows for the production of items that cannot realistically be produced in any other method. I have made some simple herringbone gears where the teeth are in a herringbone pattern. For me, with even a simple 3D printer it is no more difficult than making a regular gear. But to make it conventionally is going to be very difficult.
For the different 3D printing technologies each has its own strengths and weaknesses. For Fused Deposition Modelling (FDM), the current technology that most DIY hobbyists are playing with but also exists on a commercial and better quality scale as well, the issue is cohesion of the laminations or layers. Even when using something like ABS the resulting product is never going to be as strong as with a similar item that was injection moulded. Nor will the surface finish match something that was made in a decent mould. With Stereolithography the cost of the materials is expensive and the production is slow. Within the hobbyist environment this is just starting to appear. The quality is very high, you really have to look very hard to see the layers it was created with, but the parts are also fragile and would have a failure rate that would be unacceptable. And with Laser Sintering, the third general technology within 3D printing, you can do metal, and fairly high detail as well, but the product is porous. The laser is unable to, realistically at a reasonable cost or production rate, melt the materials to create an absolutely solid object. It is close and you are not going to notice the difference but you are probably not going to want to have the part for an high stress function. Of course with that said when someone throws a lot more money at something the quality can improve but those additional costs go up far faster than the increase in quality.
What I want to start to experiment with in the next while is to incorporate other, more conventional technologies, along with 3D printing. Where I start to print out something on a 3D printer and then use other manufacturing technologies, such as milling or a lathe, to finish or modify the part. My ideal experiment would be to have a "pallet" that can fit into various machines and provide a constant 0,0,0 reference point for each of those machines. could print something on the 3D printer, bring it to a CNC mill and have the part worked on there, bring it to a laser cutter/engraver for further work, etc. I could alternate the movement of the part to best accommodate the strengths of each particular machine. I could even have it show up several times at any particular machine if needed.
In the recent past there has been some controversy about the ability to 3D print firearms on machines that consumers have the ability to acquire, although for even a low end commercial system they are still not inexpensive. The quality is nothing close to that of conventional manufacturing and the product life span is also significantly shorter, even to the point of failure with the initial use. A metal workshop, equipped with a mill and a lathe, would still produce a far superior product that is both safer for the user, more capable of fulfilling the design requirements, and would last significantly longer in use.
For me a film holder would have the same higher quality demand as a firearm. I want my film to easily slide into the holder and to be as flat as possible, considering that gravity is going to effect the flatness. Those tolerances, especially in a regular production environment, are not going to be met by 3D printing. But on the other hand I want to show you what my new film holder design is going to look like I will print out a sample based on my new design. You can handle it, probably put film into it, and probably be able to test it in your camera. Do you like it? Is there something that we should change with it? We can put your corporate logo right here like this or would you like it here instead, and we have a sample of that as well. And I can give some to the people making the injection moulds so that they can see exactly what my product is supposed to look like.
Sorry for the long post.
Richard