---
title: "Design a bracket on your phone in five minutes"
description: "An L-bracket with four screw holes, made on a phone with the hand tools: start from a plate, add the upright, drill the holes with the M4 preset, measure, download. Where the AI saves you a minute."
canonical: https://speakcad.com/blog/design-a-bracket-on-your-phone
published: 2026-10-04
updated: 2026-10-04
publisher: SpeakCAD
---

# Design a bracket on your phone in five minutes

> An L-bracket with four screw holes, made on a phone with the hand tools: start from a plate, add the upright, drill the holes with the M4 preset, measure, download. Where the AI saves you a minute.

The shelf is up, the bracket that came with it is missing, and the shop is closed. You have a printer and a phone. Here is the bracket, from nothing to G-code, in the time it takes the printer to heat up. No account is needed to try the tools on the live demo; a free account downloads the file.

## The part

An L-bracket: a 60 by 40 mm base, 4 mm thick, with an upright 60 mm wide, 40 mm tall and 4 mm thick along the back edge. Two M4 holes in the base, two in the upright, 40 mm apart. Rounded corners on the base so it does not catch. That is a bracket that holds a small shelf, a sensor box or a strip light.

## Minute one: the base

Open SpeakCAD and, on the new model screen, under **Start from a shape**, tap **Plate**. It opens in the editor as a plate with rounded corners. Tap it: its sizes appear as numbers. Type 60 for the width, 40 for the length, 4 for the thickness. It recompiles as you type.

The corners are already rounded (the plate starts with a 4 mm radius). To soften them more, tap **Round** in the rail, tap the top face, slide the **Radius** to 6 and press **Apply round corners**.

## Minute two: the upright

Tap **Add** in the rail. Pick **Rectangle** for the shape. Set **Width** 60, **Length** 4, **Height** 40. Now tap the top face of the plate about 2 mm in from the back edge: the tab stands centred on your tap, so a 4 mm thick tab tapped 2 mm from the edge sits flush with it. Zoom in with two fingers first; it makes the tap easier. Press **Apply add**.

The upright appears as a new part, selected, with its own card: Width, Length, Height, nothing else. If it landed a millimetre off, **Remove** it on that card and tap again; that is faster than reading about it.

## Minute three: the holes

Tap **Hole**. Tap the top face of the base, near the front left corner, roughly 10 mm in from each edge. The card shows **Diameter** with the presets: tap **M4** (4.5 mm, a clearance size that a printed hole comes out right for). Tap **Through**. Press **Apply hole**. Do the same near the front right corner.

Now the upright. Turn the model with one finger so you see the front of the upright, tap **Hole** again, tap the upright's face about 10 mm from the top and 10 mm from the left edge, **M4**, **Through**, **Apply hole**. Again on the right.

Four holes, each a feature with a diameter and depth you can change later by tapping it.

## Minute four: check

Tap **Measure**. Tap the centre of one base hole, then the other: the overlay shows the distance with its ΔX, ΔY and ΔZ. You want 40 mm, give or take what your thumb did. If one hole is off, Remove it and tap again. Tap a face of the upright and the measure card also shows the face size and the wall thickness: 4.0 mm, as typed.

Nothing so far has spent a credit. The tools, the recompiles and the measurements are free.

## Minute five: download

Tap Download. STL or 3MF for your own slicer, or G-code sliced with your printer's own profile (380+ printers). A bracket shaped by hand from a starter downloads free with a free account; G-code is 5 credits unless you are on Pro or Unlimited. Print it flat on the base, 3 or 4 walls, 30% infill, no supports.

## Before you start: the three numbers to measure

A bracket is only as good as the measurements you walk up to the phone with, and a ruler is enough for all three.

- **The screws you own.** The presets are clearance sizes for metric machine screws: M3 is 3.4 mm, M4 is 4.5 mm, M5 is 5.5 mm. For a wood screw, measure the thread's outer diameter and use the preset just above it (a 4 mm wood screw goes through an M4 hole). For a screw whose head should sit flush, keep the hole as it is and ask the AI for a countersink later.
- **The spacing.** Measure between the centres of the existing holes in the wall or the shelf, or the width of the thing the bracket holds. That is the distance you check with Measure in minute four.
- **The thickness.** 4 mm is right for a shelf bracket that holds a few kilos; 3 mm is fine for a strip light or a sensor; 6 mm if you intend to stand on it. Thickness is a number you type on the plate and on the upright's card, so it can change after the first print without starting over.

## Print settings that matter for a bracket

Lay the base flat on the bed; the upright then prints as a vertical wall with no overhang, so no supports. Use 3 to 4 walls, because a bracket's strength is in its perimeters, not its infill, and 30% infill or more. PLA is fine indoors; PETG for a shed, a bathroom or a car. If the shelf is heavy, print a second one and share the load, which is cheaper than redesigning.

The weak point of any L shape is the inside corner where the two legs meet, along the layer lines. A 3 mm fillet or a pair of gussets there changes the bracket from something that snaps under a heavy shelf to something that holds it, and both are a sentence to the AI, below.

## Where the AI saves you a minute

Two things the hand tools do not do on this bracket, and what they cost:

| Change | How | Cost |
|---|---|---|
| A fillet where the upright meets the base, so it does not crack | Type "add a 3 mm fillet between the upright and the base" | 2 credits |
| A 45° gusset on each side, for a heavier load | Type "add 4 mm thick triangular gussets on both sides, 20 mm" | 2 credits |
| Round the top edges of the upright | Type it, or press the Round card's "Ask the AI to round just this edge" button | 2 credits |
| Make the whole bracket 5 mm wider | Tap the plate and type 65. Hand edits stay where you tapped them: retype the upright's Width, then Measure the holes and Remove and re-tap any that should move | Free |
| Move a hole 3 mm | Remove it and tap again | Free |

Once the AI has touched the model, its download spends 4 credits; a small fix after a test print (one hole a bit wider) re-downloads free. The AI keeps the holes and the upright you made by hand.

## Or type the whole thing

If you would rather describe it than tap it, the prompts below open in the editor. One request is 2 credits, and the bracket arrives with the fillet and the gussets already in. Then the hand tools are still there for the hole you forgot.

## Prompts to try

- An L-bracket: base 60 x 40 x 4 mm, upright 60 x 40 x 4 mm along the back edge, a 3 mm fillet between them, two M4 clearance holes (4.5 mm) in each leg 40 mm apart and 10 mm from the edges, corners rounded 6 mm. ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DAn%2520L-bracket%253A%2520base%252060%2520x%252040%2520x%25204%2520mm%252C%2520upright%252060%2520x%252040%2520x%25204%2520mm%2520along%2520the%2520back%2520edge%252C%2520a%25203%2520mm%2520fillet%2520between%2520them%252C%2520two%2520M4%2520clearance%2520holes%2520(4.5%2520mm)%2520in%2520each%2520leg%252040%2520mm%2520apart%2520and%252010%2520mm%2520from%2520the%2520edges%252C%2520corners%2520rounded%25206%2520mm.))
- A shelf bracket for a 200 mm deep shelf: 4 mm thick walls, a 45° gusset between the two legs, three 4.5 mm screw holes in each leg, printed flat. ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%2520shelf%2520bracket%2520for%2520a%2520200%2520mm%2520deep%2520shelf%253A%25204%2520mm%2520thick%2520walls%252C%2520a%252045%25C2%25B0%2520gusset%2520between%2520the%2520two%2520legs%252C%2520three%25204.5%2520mm%2520screw%2520holes%2520in%2520each%2520leg%252C%2520printed%2520flat.))
- A wall bracket for a 30 mm round sensor box: a 50 x 50 x 4 mm plate with two 4.5 mm holes 30 mm apart and a 32 mm ring 10 mm tall standing on it. ([open in SpeakCAD](https://app.speakcad.com/signup?next=%2F%3Fprompt%3DA%2520wall%2520bracket%2520for%2520a%252030%2520mm%2520round%2520sensor%2520box%253A%2520a%252050%2520x%252050%2520x%25204%2520mm%2520plate%2520with%2520two%25204.5%2520mm%2520holes%252030%2520mm%2520apart%2520and%2520a%252032%2520mm%2520ring%252010%2520mm%2520tall%2520standing%2520on%2520it.))

## FAQ

### Can I really design a bracket on an iPhone or an Android phone?

Yes, in the browser: Safari or Chrome, no app. The hand tools sit above the chat, the cards open from the bottom of the screen, and the part recompiles on the phone, usually in under a second. The live demo lets you try the tools without an account.

### How strong is a printed bracket?

Print it flat on its base with 3 or 4 walls and 30% or more infill, in PETG for a warm or damp place. The weak point is the inside corner between the two legs along the layer lines: a 3 mm fillet or a gusset there, which is one AI request, roughly doubles what it takes to crack it.

### What does the bracket cost to make?

Shaping a part by hand (a hole, a cut, an added tab, an extruded face, rounded corners) and downloading what you shaped are free. Each AI request spends 2 credits, a download of AI work 4 credits, and G-code 5 more. A bracket made only with the tools downloads free with a free account. The fillet or the gussets are 2 credits, and the download of a model with AI work spends 4 credits; G-code is 5 more unless you are on Pro or Unlimited.

### Can I change the bracket after printing it?

Tap any feature and retype its number: a hole from 4.5 to 5.5 mm, the plate from 60 to 70 mm. Remove a hole and tap it elsewhere. The model keeps every version, so you can go back.

## About SpeakCAD

SpeakCAD is the easiest way to design a part with real dimensions on your phone: shape it with simple tools or describe it to the AI, and download a print-ready STL, 3MF or G-code sliced for your printer.

SpeakCAD works inside ChatGPT and Claude as a plugin (an MCP server): ask the assistant for a part with its measurements and SpeakCAD's own CAD AI designs it, shows it in 3D in the chat and hands over a print-ready STL, 3MF or G-code sliced for your printer.

- Live demo, no account: https://speakcad.com/demo
- In ChatGPT, Claude and other MCP clients: https://speakcad.com/chatgpt-plugin, https://speakcad.com/claude-connector, https://speakcad.com/mcp-server
- Pricing: https://speakcad.com/pricing
- FAQ: https://speakcad.com/faq
- Site index for AI assistants: https://speakcad.com/llms.txt