How to Make Your Own Recycled Sunglasses from Plastic Waste
You have a pile of plastic bottle caps sitting in a box. You want to turn them into something functional, something wearable, something that proves waste material has real value. Recycled sunglasses are one of the most rewarding products you can make with a desktop injection moulding machine, and the process is more straightforward than you might think.
This guide covers everything you need: the material, the equipment, the mould, and the five steps from waste to finished pair.
Why recycled sunglasses work so well as a first product
Most people starting out with desktop injection moulding want to make something that proves the concept. Coasters and combs are fine, but sunglasses get a reaction. They are functional, they look professional, and they demonstrate what recycled plastic can become when paired with the right mould.
Recycled plastic sunglasses also have a clear commercial angle. Brands like Waterhaul and Sea2see have built entire businesses around recycled eyewear, selling frames at premium prices. Those companies rely on industrial scale manufacturing. With desktop injection moulding, you can produce sunglasses at home, in a workshop, or in a classroom, using waste material you collected yourself. That is circular manufacturing at its most tangible: plastic that would otherwise sit in landfill, transformed into a wearable product with real market value.
Several Sustainable Design Studio customers have already proven this at volume. Pangea in Indonesia has produced over 1,500 pairs of recycled sunglasses from mangrove waste using Sustainable Design Studio machines and moulds.
What you need before you start
The materials list is short. You need recycled polypropylene (PP), a desktop injection moulding machine, a sunglasses mould, replacement lenses, and a set of small screws for the arms.
Plastic: Polypropylene is the recommended material. It flows well at 210°C, produces a smooth finish, and is widely available as recycled feedstock. Bottle caps are an excellent source. On the Injection Mini V2, you can load bottle caps directly into the barrel without shredding first, thanks to the 25mm hopper opening. If you want to use other PP sources, shredding to a consistent flake size with the Shredder Mini V2 will give you better results.
Machine: The sunglasses mould is compatible with two Sustainable Design Studio machines. The Injection Mini V2 (from £925 as a kit) uses pneumatic injection and has an 80cm³ shot volume, which is more than enough for sunglasses frames and arms. The Arbour Injection Machine V2 (from £1,600 as a kit) offers a larger 170cm³ shot size with manual rack and pinion injection, making it well suited to higher volume production or larger products alongside your sunglasses.
Both machines run on standard mains power (110v or 220v) and use no more electricity than a kettle. The Injection Mini V2 requires an external air compressor (minimum 8 bar, 24 litre tank, not included). The Arbour is entirely manual, so no compressor is needed.
Mould: The Sustainable Design Studio Sunglasses Mould (Premium Mould #6) is a CNC machined aluminium mould priced from £1,450. A custom branding option is available at £1,650, allowing you to engrave your own logo directly into the mould so every pair carries your brand. The mould consists of two separate moulds: one for the frames and one for the arms.
Lenses and hardware: The mould is designed around commonly available replacement lenses for Oakley style sunglasses. This means you can source affordable, high quality lenses online without needing custom optics. Small screws connect the arms to the frames.
The lens groove that saves you hours
This is the detail that sets the Sustainable Design Studio sunglasses mould apart. The mould includes a built in lens groove in the frame design. Once you remove the frames from the mould, you pop the lenses straight into the groove. No cutting, no filing, no post processing to create a channel for the lens to sit in.
Many other sunglasses mould designs require you to manually cut a lens groove after moulding, which is time consuming, inconsistent, and prone to error. The Sustainable Design Studio design eliminates that step entirely, which matters when you are producing more than a handful of pairs.
Five steps from plastic waste to finished sunglasses
The production process follows the same injection moulding workflow you would use for any product, with a straightforward assembly step at the end.
Step one: Prepare your plastic. Collect clean, dry recycled polypropylene. Bottle caps are ideal. Sort by colour if you want a consistent look, or mix colours for a marbled effect. If using larger PP items, shred them to a uniform flake size first.
Step two: Set up your machine. Set the barrel temperature to 210°C and allow eight to 12 minutes for heating, followed by a 10 minute heat soak so the barrel temperature fully stabilises. Pre heat your sunglasses mould to 40 to 60°C using a heat gun or small oven. This step is critical: a cold mould causes the plastic to cool too quickly, leading to incomplete fills and poor surface finish.
Step three: Inject the frames. Load your PP into the barrel, attach the frame mould, close the safety door, and inject. Hold pressure briefly after the stroke ends to pack the mould and reduce sink marks. Allow the plastic to cool, then remove the mould and demould the frames while still warm.
Step four: Inject the arms. Repeat the process with the arm mould. You will get a pair of arms from each shot. Keep the same temperature settings and ensure your mould is warm before each injection.
Step five: Assemble. Pop the replacement lenses into the frame's built in lens groove. Attach the arms to the frames using the small screws. That is it: a finished pair of recycled sunglasses, ready to wear or sell.
Three styles to choose from
Sustainable Design Studio offers three sunglasses frame styles, each based on widely recognised designs: Frogskin, Holbrook, and Sunto. All three use the same commonly available replacement lenses, so you can offer variety to customers without sourcing different optics for each style.
Whether you are building a small recycled eyewear brand, running workshops, or proving that waste material has commercial value, these styles give you a range that appeals to different tastes.
Scaling up: from hobby to production
A single pair of recycled sunglasses costs very little in raw materials. Recycled PP runs at roughly £1 to £2 per kilogram, and each pair of frames uses only a fraction of that. Compare this to virgin filament for 3D printing at £17 to £25 per kilogram, and the economics of injection moulding become clear.
The Injection Mini V2 can produce a pair of frames in minutes once you have dialled in your settings. If you are running a workshop or small business, that means dozens of pairs per session. The Arbour's larger shot size and manual operation make it well suited to longer production runs where you want to keep output moving without relying on a compressor.
Sustainable Design Studio also produces custom branded sunglasses on request if you want professionally manufactured pairs carrying your own branding.
Where to go from here
If you already own a Sustainable Design Studio injection machine, the sunglasses mould is a natural next step. Sustainable Design Studio provides a complete step by step guide on the Resources page covering every detail of the production process, from bottle cap preparation through to finished assembly. That guide is available to all machine owners at sustainabledesign.studio/howto-sunglasses.
If you are still exploring whether desktop injection moulding is right for you, the sunglasses project is a useful benchmark. It shows what a compact, desktop scale machine can produce when paired with well designed tooling and a proven material like polypropylene.
The waste material is already there. The machines and moulds exist. The only question is what you want to make from it.