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YOU CAN TURN OLD BEER BOTTLES INTO TERRAZZO

Smash green beer bottles with a hammer, pour fine mortar over the shards, then sand the slab smooth — the glass appears as you polish.

by Grey Element

FULL CAD BOM FIRMWARE DOCS

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difficulty
●●●○○
time
a weekend
license
license not specified
repo
repo 0 stars

WHAT YOU’LL NEED

Videos
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COMPAREE VERDICT

This is a materials transformation project, not a parametric build. You break glass bottles with a hammer inside a cloth bag, sort the shards to similar sizes, lay them rounded side down in a mold, pour a light, fine-grained, runny ready-mix mortar over the top (reinforced with plastic mesh, not fibres, which show when sanded), let it cure, then sand from 80 grit up to 1000 grit wet until the glass shows through. The blog guide walks you through each step with photos and a short materials list; the YouTube video shows the process in motion. What will actually be hard: getting an even spread of shards so the pattern looks deliberate, and sanding evenly. The guide does not give mold dimensions, a mold material, a release agent or a curing time, so you will solve those yourself. The mistakes the guide warns about are using fibre reinforcement, leaving shards too large, and laying shards rounded side up, which leaves voids. The finish depends on patience during sanding.

GOOD TO KNOW

  • —Step-by-step written guide is free on the Grey Element blog in German, with photos.
  • —YouTube video available (iG1dCEsBSLA, about 500k views, January 2022).
  • —The blog lists the basic materials (glass bottles, hammer, mortar, reinforcement mesh, sandpaper) but no exact quantities or mold design.
  • —No CAD files or mold design; you build your own mold.
  • —No licence is stated; the blog says the guide may be shared with friends.

Parts to buy

4 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Glass bottles (any colour)Find
  • Light fine-grained ready-mix mortarFind
  • Plastic reinforcement meshFind
  • Sandpaper (80-240 grit dry, 400-1000 grit wet)Find

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Can I build this?

Printnothing required
BuyGlass bottles (any colour), light fine-grained ready-mix mortar, plastic reinforcement mesh, sandpaper (80-240 grit dry, 400-1000 grit wet), mold material and release agent (not specified in the guide)
ToolsHammer, cloth bag, random orbital sander, gloves, eye protection, dust mask
SkillsJudging shard size by eye, pouring mortar without shifting the glass, and patient, even sanding.
TimeA weekend; the guide gives no times or curing time.
Cost$; the guide gives no prices
SafetyFlying glass when breaking bottles (keep them inside the cloth bag; the guide says gloves are a must; wear eye protection). Cement and glass dust when dry sanding: wear a mask. Store broken glass away from children.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

Making Terrazzo out of old glass bottles6:39

Grey Element, January 2022, about 500k views. The process from breaking bottles to final sanding.

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Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the blog guide in German (or use a browser translator) (Photos of each step, written instructions and a short materials list.)
  2. 2.Watch the YouTube video for the sanding sequence and how the glass reveals itself (Shows the process in motion, including sanding.)
  3. 3.Source your bottles and decide on a mold size(The guide does not specify mold design, dimensions or release agent; you will need to decide based on what you are making.)

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • Using fibres for reinforcement instead of plastic mesh: fibres become visible when you sand.
  • Leaving shards too large: break oversized pieces again so they are similar in size.
  • Laying shards rounded side up instead of down: the guide says rounded side down avoids voids.
  • Choosing a coarse mortar: the guide uses a light, fine-grained, runny ready-mix so it fills around the glass.
  • Sanding unevenly: work through the grits patiently until the glass shows evenly.
  • Not soaking the wet sandpaper first: the guide pre-soaks it so it does not clog.

Can I use different coloured glass or mix colours?

Yes. The guide says waste glass comes in different colours and they can be combined. Grey Element used green beer bottles.

What kind of mortar do I need?

A light-coloured, fine-grained, very runny ready-mix mortar that only needs water, so it fills around the glass.

Do I need a concrete grinder or will a random orbital sander work?

The guide says concrete is usually ground with special concrete grinders with diamond discs, but a random orbital sander also works, and that is what Grey Element used.

How thick should the slab be?

The guide does not give dimensions. Thickness depends on your mold and intended use.

Is this food-safe for a cutting board or countertop?

The guide does not address food safety.

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Discussion1

FROM THE COMPAREE TEAM

Grey Element laid the shards rounded side down to avoid voids, then sanded up to 1000 grit until the glass appeared. What would you make first: a coaster, a tray, or something bigger?

CompareeTEAM1d ago

Practical notes from our verification: the blog guide is in German, and the YouTube video shows the process in motion. The biggest gap is the mold: the guide does not give dimensions, a mold material, a release agent or a curing time, so you are solving that part yourself. The guide is explicit that fibre reinforcement becomes visible when you sand, so use plastic mesh. It also does not give quantities, so you choose the mix yourself based on the description: light-coloured, fine-grained, very runny ready-mix mortar that only needs water.

Grey Element

Grey Element is a German DIY blog and YouTube channel (Grey Element Projects) focused on concrete projects. The terrazzo video was published in January 2022 and has about 500,000 views; the blog guide is in German, with photos.

Web

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  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
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