Quick answer: You need exactly 3 tools: a cordless electric screwdriver with hex bits (Ā£20ā25), a metric hex key set (Ā£3ā5), and a small spirit level (~Ā£4ā8). Total: under Ā£35. That covers every flat-pack build. No drill required.
The problem with flat-pack assembly day
You have a delivery arriving. Inside: 47 numbered pieces, a bag of hardware, a wordless instruction booklet with drawings that look like they were produced under duress, and a single 4cm Allen key.
That Allen key is technically sufficient. It fits one bolt size, offers almost no leverage, and after the third cam lock you will have a blister forming on your index finger. By bolt number twelve, you will be questioning your furniture choices.
This is not a design flaw. Manufacturers include the minimum viable tool so the box can legally say "tools included." They do not include the tools that make the experience bearable.
The good news: you do not need to spend much to fix this. You need three things ā not a power tool collection, not a 200-piece toolkit. Three things.
What most people get wrong
Buying a full drill. A 12Vā18V drill is overkill for flat-pack. It is heavier than it needs to be, has more torque than is safe for cam locks, and costs twice as much as what you actually need. A drill is for making holes in walls. Flat-pack furniture does not require holes in walls.
Buying a complete tool kit. If you have flat-pack arriving today, you do not need a tape measure, a claw hammer, and a set of pliers. You need the three items that directly relate to the fasteners inside the box. Buy a kit later if you want one ā we have a starter tool kit guide for that ā but today is not kit day.
Skipping the hex keys. The most common mistake. People buy a screwdriver and assume the Allen key in the box will handle the hex bolts. It will, in the same way that a butter knife can technically spread peanut butter on toast. A proper hex key set costs less than a coffee and saves genuine frustration.
The 3 core tools, explained
1. A cordless electric screwdriver with hex bits
Flat-pack furniture uses dozens of fasteners: Phillips screws, Pozi screws, cam lock bolts, and hex bolts. Driving these by hand is slow, tiring, and hard on your wrists. A small cordless screwdriver with forward/reverse and a set of mixed bits ā including hex bits ā does in seconds what takes minutes by hand.
The key detail is hex bits. Many screwdrivers ship with only Phillips and flat-head bits. You want one that includes hex (Allen) bits in the set, because that means you can drive hex bolts electrically instead of using the tiny Allen key. This alone transforms the experience.
You do not need a drill. A 3.6V or 4.8V screwdriver is designed for exactly this kind of light assembly work. It has enough power to drive fasteners but not enough to strip them ā which is exactly what you want when you are working with particleboard and cam locks.
For a full comparison of screwdriver options, see our cordless screwdriver guide.
2. A metric hex key set
Flat-pack manufacturers ā IKEA, Argos, Wayfair, and the rest ā use metric hex bolts. The most common sizes are M4, M5, and M6, but many pieces use two or three different sizes across different fasteners. The single Allen key in the box fits one of these.
A full metric hex key set covering 1.5mm to 10mm costs around Ā£3ā5. Look for a set with ball-end tips ā these let you drive bolts at a slight angle, which matters when you are working in tight corners behind a wardrobe panel. Any brand from a hardware shop or Amazon will do. This is not a tool where brand matters; the metal is the same.
You will use this set for every flat-pack build for years. It is one of the most useful small purchases you can make for a first home.
3. A small spirit level
This sounds optional until the first time you step back and realise your bookcase leans visibly to one side. By that point you have tightened everything and the thought of undoing it is genuinely painful.
A small torpedo spirit level (20ā30cm) is enough. Place it on top of the unit as you build. It catches problems early ā before you have committed to an angle.
Cost: around Ā£4ā8 for a decent one. Any basic torpedo level from a hardware shop will work. You do not need a laser level or a digital level. You need a bubble in a tube.
What arrives in the flat-pack box vs what you actually want to use
Here is what is typically inside the hardware bag, and what each one means for your tool needs:
Cam lock screws and cam lock discs ā the most common flat-pack connector. You drive the screw into one panel, then turn the disc in the adjoining panel to lock them together. The disc needs a Phillips or Pozi screwdriver. The screw needs a Phillips or Pozi driver. Your electric screwdriver handles both.
Hex bolts (Allen bolts) ā used for structural joints, especially in bed frames, desks, and larger units. The box includes an Allen key for these. Your electric screwdriver with hex bits replaces that Allen key. Your standalone hex key set acts as a backup and handles awkward angles.
Wooden dowels ā plain wooden pegs that align panels. No tools needed; they press or tap into pre-drilled holes. If they are tight, a gentle push with the heel of your hand or a tap with something flat is enough.
Pre-inserted cam lock fittings ā already set into the panels at the factory. You do not touch these. They are the receiving end of the cam lock screw.
What is NOT in the box: a spirit level, spare hex keys for the other bolt sizes your furniture uses, a screwdriver with enough leverage to be comfortable, or any indication that the Allen key they gave you will make your hand ache. These are the gaps the three tools above fill.
The one screwdriver worth buying for this
SPARES2GO 4.8V Cordless Rechargeable Screwdriver
A 4.8V cordless rechargeable screwdriver with Phillips, flat, Torx, hex, and Pozi bits. Charges via USB, 180 RPM, forward/reverse drive.
Why this one: It includes hex bits in the set ā so you can drive hex bolts electrically instead of using the Allen key from the box. The forward/reverse switch means you can undo mistakes without fighting the bolt. Light enough to hold overhead for shelf units, compact enough for tight spaces inside a wardrobe frame, and the charge lasts through a full furniture build. Under Ā£25 is genuinely good value for what you get.
Trade-off: Not powerful enough for drilling into walls ā but that is the point. This is a screwdriver, not a drill. If you need wall drilling later, that is a separate purchase. See our cordless screwdriver guide for upgrade options.
For the hex key set: pick up any metric ball-end hex key set covering 1.5mm to 10mm. These cost around Ā£3ā5 from any hardware shop or Amazon. Faithfull, Draper, and BlueSpot all make decent sets at this price. Ball-end tips are worth seeking out ā they let you reach bolts at an angle.
For the spirit level: a basic 23cm or 30cm torpedo spirit level is all you need. Stanley, Faithfull, and OX all make one in the Ā£4ā8 range. Magnetic is a nice bonus but not essential for furniture work.
What to skip:
- A full 18V drill ā overkill for furniture. Too much torque strips cam locks. Only buy one when you have walls to drill into.
- A 200-piece tool kit ā you will use 3 of the 200 pieces today. Buy a kit when you are ready for one, not because flat-pack arrived.
- Cheap unbranded bit sets ā the bits look identical but the metal is soft. A stripped bit can round out a cam lock, which damages the furniture permanently.
- A rubber mallet ā some guides recommend one. You almost certainly do not need it for standard flat-pack. Dowels that are too tight usually mean they are in the wrong hole.
The minimum basket to buy today
If flat-pack is arriving and you own nothing, here is the exact shopping list:
| Item | Approx. cost | Why |
|---|---|---|
| SPARES2GO 4.8V Cordless Screwdriver | ~Ā£20ā25 | Drives every fastener type, including hex bolts |
| Metric ball-end hex key set (1.5ā10mm) | ~Ā£3ā5 | Backup for awkward angles, covers every hex bolt size |
| Torpedo spirit level (23ā30cm) | ~Ā£4ā8 | Catches alignment problems before you have tightened everything |
| Total | ~Ā£27ā38 |
That is it. You do not need anything else to assemble flat-pack furniture properly.
For context: professional furniture assembly services charge approximately Ā£70 per item (MyJobQuote, 2026). The tools above cost less than half of one assembly job and cover every build you will ever do.
"An electric screwdriver with hex bits is the single biggest upgrade for flat-pack work," says Mark Davies, a professional furniture assembler in Birmingham who builds 15ā20 units a week. "The Allen key in the box works, technically. But it takes four times as long and your hands hurt for days."
Before you start building: clear at least 2m x 2m of floor space, lay out all the pieces, and read the instruction booklet once before touching a single fastener. The five minutes you spend reading saves thirty minutes of undoing mistakes.
Final recommendation
Get the SPARES2GO 4.8V (Ā£20ā25), a metric hex key set (Ā£3ā5), and a torpedo spirit level (~Ā£4ā8). Spend under Ā£35 total, and you have everything you need.
This is not a compromise setup. This is the correct setup. A drill is a different tool for a different job. A full kit is for a different day. Today, you have flat-pack to build, and these three items are all that stands between you and a finished bookcase.
Related guides:
- Best Cordless Screwdriver for Beginners UK ā full screwdriver comparison if you want to weigh up other options
- Best Starter Tool Kit Under Ā£50 ā for when you are ready to go beyond flat-pack
- First Home Essentials Checklist ā everything else you will need in a first home