DIY Injection Molding: Is a Desktop Machine Worth It?
DIY injection molding is one of those topics where the internet gives you either breathless hype or zero practical detail. If you have been looking at desktop injection moulding machines and wondering whether they are a serious tool or an expensive novelty, you are asking the right question. The honest answer: it depends on what you want to make, how many you need, and whether you are prepared for a learning curve.
This post breaks down the real costs, the realistic output, and the types of projects where a plastic injection molding machine for home or workshop use actually pays for itself.
What Does DIY Injection Moulding Actually Involve?
Desktop injection moulding follows the same principle as industrial injection moulding, just at a smaller scale. You heat thermoplastic (virgin pellets or recycled waste), force it into a metal or resin mould under pressure, wait for it to cool, and pop out a finished part.
The full setup includes three things: a machine to melt and inject the plastic, a mould that defines the shape of your part, and a source of plastic (pellets, shredded waste, or even whole bottle caps on some machines).
The process itself is not complicated. Most people can produce their first part within an hour of unboxing. The learning curve is in dialling in temperature, pressure, and timing for consistent results across different plastics and mould geometries.
The Real Costs
Here is where most guides get vague. Let's be specific.
The machine. Entry-level desktop injection moulding machines start from around £200 for simple hand-operated extruder types, up to £925 for semi-automatic pneumatic machines like the Injection Mini V2, and £1,600 for larger manual machines like the Arbour Injection Machine. You can spend more on fully automatic bench-top systems from other manufacturers, but the £200 to £1,600 range covers most hobby and small-production needs.
The mould. This is the part people underestimate. A custom CNC aluminium mould from a mould maker typically costs £500 to £3,000 depending on complexity. However, desktop users have cheaper options. 3D printed resin moulds cost under £10 in material and work well for 50 to 500 shots. SDS sells ready-made Premium Moulds for specific products (bottle openers, coasters, sunglasses, beads) starting from around £150, which removes the design step entirely.
Plastic. Virgin injection grade PP pellets cost roughly £2 to £4 per kg. Recycled plastic from bottle caps or shredded waste is essentially free if you collect it yourself. One kilogram of PP produces roughly 14 shots on an 80 cm3 machine.
Extras. A compressor is needed for pneumatic machines (£100 to £300 for a basic 24 litre, 8 bar unit). Fume extraction is recommended for any indoor setup. A heat gun for pre-heating moulds costs under £30.
Total realistic startup cost: £400 to £1,500 for a capable setup that can produce real products. That is less than the cost of a single custom mould from an industrial supplier, and it gives you the ability to make unlimited products from it.
When a Desktop Machine Is Worth It
A hobby injection molding machine makes financial and practical sense in specific situations.
You need more than 10 identical parts. 3D printing is slower and weaker for production runs. Injection moulding produces a finished, consistent part every 1 to 4 minutes. If you need 50 bottle openers for an event or 200 keyrings for a shop, injection moulding is dramatically faster than printing them one by one.
You want to use recycled plastic. This is where desktop injection moulding has a unique advantage over nearly every other making process. You can take bottle caps from a collection bin, shred them (or feed them directly into machines with wider barrels), and turn them into finished products. No other desktop manufacturing tool does this as cleanly.
You are prototyping for eventual mass production. Testing your product design in the actual production material (moulded PP, HDPE, or ABS) gives you data that 3D printed prototypes cannot. Wall thickness, surface finish, shrinkage, material feel: all behave differently in a moulded part versus a printed one.
You teach or run workshops. Desktop machines are small, safe (enclosed designs with safety interlocks), and visually impressive for demonstrations. Students can go from CAD file to 3D printed mould to injected plastic part in a single session.
You sell small-batch products. Handmade markets, brand merchandise, promotional items, or niche products in quantities of 50 to 5,000 units per month sit perfectly in the desktop injection moulding sweet spot.
When It Is Not Worth It
Equally important to answer honestly.
You only need one or two copies of something. 3D printing or hand carving is faster and cheaper for one-offs. Injection moulding only makes sense when you are repeating the same part multiple times.
Your parts are larger than roughly 170 cm3. Desktop machines have a maximum shot size. The biggest SDS machine (the Arbour) handles 170 cm3 per shot, which covers most small consumer products. If you need something bigger, you are looking at industrial equipment.
You need engineering-grade tolerances. Desktop machines produce good, consistent parts, but they are not CNC machining centres. If your application demands tolerances tighter than +/- 0.2 mm, an industrial setup is more appropriate.
You have no patience for process tuning. Each new plastic type and mould combination needs temperature, pressure, and timing adjustments. It is not plug-and-play in the way that a well-calibrated 3D printer can be. The learning curve is real, even if it is short.
What Can You Actually Make?
To give you a concrete sense of what desktop injection moulding produces, here are some examples from real SDS users.
Bottle openers, keyrings, beads, combs, coasters, plant pots, sunglasses frames, trolley coins, rulers, phone stands, soap dishes, buckles, carabiners, and custom branded merchandise. All made from recycled plastic, all production quality.
The limiting factor is not the machine. It is the mould. If you can design or source a mould for your product, the machine will make it reliably.
How SDS Machines Compare
SDS makes three machines that cover different points on the cost, automation, and capacity spectrum.
The Injection Mini V2 (from £925) is the most popular starting point. It is semi-automatic: you load plastic, set the temperature, press a button, and the pneumatic piston does the injection. Shot volume is 80 cm3 (roughly 71 g of PP). It supports eight plastic types including PP, HDPE, ABS, PLA, PETG, PS, TPU, and LDPE. It weighs 25 kg, runs on 110 v or 220 v, and needs an external compressor (8 bar, 24 litre tank, not included). One-button operation makes it the easiest to use consistently.
The Extruder Mini V2 (from £950) is hand cranked (or drill powered for faster operation) and ultra-portable at 10 kg. It doubles as an extruder for creating filament or continuous profiles, and can also inject into moulds. No compressor needed. Best for mobile workshops, classroom demos, and anyone who values portability over automation.
The Arbour Injection Machine (from £1,600) uses a rack and pinion mechanism for manual injection with a 170 cm3 shot size, double the Injection Mini V2. It weighs under 30 kg, needs no compressor, and runs on 110 v or 220 v. Best for larger products and higher-volume production where the bigger shot size justifies the higher price.
The Honest Verdict
A desktop injection moulding machine is worth it if you plan to make the same part more than a handful of times, especially from recycled plastic. The startup cost is modest compared to almost any other manufacturing method, and the per-unit cost drops to nearly zero once you have your mould.
It is not worth it if you only need one-off parts, if your designs change constantly, or if you are not willing to spend a few hours learning the process.
For most makers, educators, and small-batch producers, the answer is yes. It pays for itself quickly, and the ability to turn waste plastic into real products adds something that no other desktop tool offers.