4 Interesting Alternatives to 3D Printing

3D printing has taken the world by storm, but other ways of creating objects might make for some suitable alternatives to 3D printing. These different methods might not be as accessible to everyday folks as a 3D printer is, but they could be in the future. 

Some of the most interesting alternatives to 3D printing include 4D printing, rapid liquid printing, injection molding, and thermoforming. Some of these processes are additive manufacturing methods like 3D printing, but others use different ways to create complex objects. 

In this article, I’ll explore some of the most fascinating and promising alternatives to 3D printing, discussing how they work, some applications for them, and the materials you can use with them. I’ll also discuss why these alternatives could replace 3D printers in households in the future. 

1. 4D Printing 

4D Printing is a relatively new phenomenon and tricky to explain in layperson’s terms. It encapsulates any 3D printed design made from intelligent material and a clever design that changes when exposed to certain conditions. 

These conditions are:

• Heat
• Light
• Water
• Time
• Physical force

Examples of 4D-printed items are toys and robots. These structures can change shape if the user applies some input. Rubix Cubes are explicitly made for this purpose, as are slinkies and robot arms. 

4D has the same shape as 3D from the outside; the difference is that it can change forms if energy is exerted onto it, and then it takes on a whole new level of function. 

Practical Uses of 4D Printing

Besides toys and robots, 4D printing is opening up a new world of possibilities for generating functional materials and technology. 

• Water-activated furniture: Save space in your house with compact, foldable furniture that activates and opens when in contact with water. Furniture would be just as strong but with twice the convenience.  
•  Dynamic piping that can repair itself: Pipes made of flexible material can adjust their width and size according to water flow and improve themselves in the event of cracks or breakage with heat or water activation. 
• Aerospace technology: Having technology that can adapt to its environment and “heal” itself would be a significant advantage in space, where conditions are unforgiving and stakes high. 

We’re quickly ushering in the future of adaptive and dynamic technology at a level we were never able to achieve. These methods surpass 3D printing in usefulness and the range of materials they can accommodate. 

3D Printing requires a thermoplastic filament or resin and a compatible printer. However, the future of printing will allow you to use any and every material to print

For more information on how 4D printing came about and a practical demonstration of its uses, watch the below video, filmed in collaboration with the Massachusetts Institute of Technology (MIT). 

2. Rapid Liquid Printing

Rapid liquid printing (RLP) has a somewhat opposite process to injection molding. Granular carbomer hydrogel is suspended in a vat, and a machine injects liquid-curable material into the gel into a pre-specified shape through a pneumatic syringe. 

This method of machining is perhaps the most diverse form of printing in this article, as printing materials can range from concrete to silicone. 

This method isn’t a layer-by-layer process like 3D printing is. Rapid liquid printing is a much faster way of producing far larger items.

Practical Uses of RLP

RLP is being used more and more frequently and could soon overtake 3D printing in popularity. 

Some items produced through RLP include:

• Footwear
• Car parts 
• Rubber
• Foam
• Medical equipment 
• Aviation parts 

Besides being fast, it’s also more versatile. Gone are the days of waiting hours for each layer to print. Now, you can print multiple items in the same gel bath, as every item stays suspended exactly where the nozzle injected it. 

The process takes a few minutes in total. When the material has been chemically treated, it’s removed from the gel and rinsed of any excess gel. That’s it.

This footage taken by MIT perfectly illustrates the RLP process and presents examples of the tools used to create the prints and some examples of end products. 

3. Injection Molding

Injection molding is more material-efficient and produces less waste than 3D printing. It’s detailed and precise and saves on production costs using automation. 

Plastic injection molding involves melting thermoplastic polymers, usually in pellet form, and injecting them into a mold. The plastic fills the empty section of the mold, called the cavity image. 

The molten plastic or resin takes on the mold’s shape as it solidifies. 

The mold doesn’t require external cooling, saving time and significantly lowering production costs. Injection molding is quick and efficient with minimal wastage, making it a fantastic alternative to 3D printing. 

Practical Uses of Plastic Injection Molding

Examples of injection-molded products include (but aren’t limited to):

• Lego blocks
• Electrical circuit boards
• Syringes and other medical equipment 
• Disposable cutlery

NYC CNC provides an in-depth, step-by-step look at how injection molding works, which you can watch using the link below. 

4. Thermoforming 

Thermoforming, commonly known as vacuum forming, is a process where a plastic sheet is heated up and placed over a mold. A vacuum then pulls the air out of the mold, leaving the plastic shape or cooling down the sheet to solidify into the form of the mold. 

There are several methods of thermoforming:

• Vacuum forming
• Pressure forming
• Mechanical forming
• Drape folding
• Match mold forming
• Twin sheet forming
• Billow forming

For more information on how each of these processes works and what functions they’re best for, check out this guide to thermoforming. 

The structure is then trimmed to the appropriate shape and dimensions, a relatively quick and straightforward process. The plastic sheets usually consist of the following materials:

• Polypropylene (PP)
• Polyethylene Terephthalate (PET) 
• Polystyrene (PS)
• Low-Density Polyethylene (LDPE)
• High-Density Polyethylene (HDPE)
• Cellulose Acetate
• Acrylonitrile-Butadiene-Styrene (ABS)
• Polymethyl methacrylate (PMMA)
• Polycarbonate (PC)

Those familiar with 3D printing will recognize many of these materials, as they’re common for making 3D printing filaments.

They’re cost-effective, easy to work with and produce sturdy prints regardless of size or detail. 

Practical Uses of 3D Printing Alternatives

These methods and materials rapidly produce high-quality structures, just as durable as products created using 3D printing, if not more.  

3D Printing is a longstanding method of creating valuable parts and objects, ranging from space travel accessories to miniature figurines. As time goes by, we’re finding new ways to utilize materials constructively with less wastage. 

3D printers are moving towards a more eco-friendly means of operating by employing plant-based materials and paper as a new printing medium. However, these materials are yet to see their final form, so we’re stuck with synthetic or chemically balanced thermoplastics for now.

Hours of productivity are also lost waiting for 3D printers to complete their tasks, whereas its alternatives can do the same job in minutes. 
Overall, there’s a very bright future for every single 3D printing alternative listed here. Over the past five years alone, scientists have made progress in leaps and bounds to phase out 3D printing and introduce a new and more sustainable era of printing.