Every DIY robotic arm — cardboard or 3D-printed, $30 or $300 — is built from the same handful of robotic arm parts. Get the components right and the build is straightforward; get them wrong (an underpowered servo, no separate supply) and the arm sags, jitters or resets. This is the complete parts list, what each component does, and how to choose it.
The six core components
Every robotic arm, hobby or industrial, is assembled from six component groups:
| # | Component | What it does | Typical choice |
|---|---|---|---|
| 1 | Actuators | Move each joint | Hobby servos (SG90 / MG996R) |
| 2 | Controller | Runs the code | Arduino / ESP32 / Raspberry Pi |
| 3 | Servo driver | Generates clean PWM | PCA9685 (16 channels) |
| 4 | Power supply | Feeds the servos | Separate 5–6V supply |
| 5 | Structure | Links, joints, base | 3D-printed / laser-cut / kit |
| 6 | End effector | Interacts with objects | Gripper / claw |
Add wiring, fasteners and tools and that’s a complete bill of materials. Let’s take each in turn.
1. Actuators — the muscles
The actuators are the motors that move each joint, and they’re the parts that most determine how the arm performs. For almost every DIY arm these are hobby servo motors: they have built-in position control, so you send an angle and the servo holds it.
- The base and shoulder carry the whole arm and need the most torque — metal-gear servos like the MG996R (≈10 kg·cm).
- The wrist and gripper carry little and can use light SG90 micro servos.
Full sizing maths is in servo motors for robotic arms. For a higher-torque, more precise arm, stepper motors replace servos at each joint. Browse servo motors and stepper motors for the parts.
2. Controller — the brain
The controller runs your code and tells each actuator what to do:
- Arduino / ESP32 — the default for motion control. Cheap, real-time, rock-solid for driving servos.
- Raspberry Pi — when you want a camera, vision or machine learning on top of the arm.
Many advanced builds use both: a Pi as the brain, an Arduino as the muscle controller. Shop microcontroller boards.
3. Servo driver — clean signals for many servos
Once an arm has more than two or three servos, driving them directly from the controller causes jitter and eats pins. A PCA9685 servo driver takes I2C commands and generates clean PWM for up to 16 servos, with a separate power input so servo current never resets your board. It’s the single best upgrade for a multi-servo arm. Shop controllers & drivers.
4. Power supply — the part beginners skip
This is the component most first-time builders get wrong. Servos draw far more current than a microcontroller’s regulator can supply, so they need a separate 5–6V power supply sized for the combined stall current of every servo. Skip this and the arm browns out and resets.
A bench supply or a buck converter both work — see powering a robotic arm for the current maths and the critical common-ground rule. Shop power & regulators.
5. Structure — links, joints and base
The structure is the physical skeleton: the links (rigid segments), the joints (where motors mount), and a base. Options, cheapest first:
- Cardboard / craft materials — the free first build.
- 3D-printed parts — rigid and precise; download STL files and print in PLA filament.
- A kit — the frame, brackets and fasteners pre-matched. See best robotic arm kits.
6. End effector — the gripper
The end effector is whatever the arm uses to interact with the world — usually a gripper. It’s driven by its own servo and mounts at the last joint. Beyond simple jaw grippers there are suction, magnetic and specialised tools — see end effector types and the gripper build guide. Shop grippers & claws.
The supporting parts
Three more part groups complete the build:
- Wiring & breadboards — jumper wires, Dupont connectors and a breadboard for prototyping the circuit before you solder.
- Sensors & encoders — optional position feedback for closed-loop control.
- Fasteners & hardware — the M2/M3 screws, nuts and standoffs that hold everything together. A mixed assortment kit saves endless trips for the one screw you’re missing.
- Tools & soldering — a soldering iron, cutters and a screwdriver set for assembly.
Accessories and attachments
Beyond the core parts, a few robotic arm accessories meaningfully extend what the arm can do. Because the end effector bolts to the last joint, swapping attachments turns one arm into several machines:
- Alternative end effectors — suction cups for flat objects, an electromagnet for steel parts, or a three-finger gripper for rounded ones. See end effector types.
- A camera for vision-guided picking — see camera & vision.
- Encoders and limit switches for closed-loop position and reliable homing.
- A tool mount for a pen, laser or rotary tool, turning the arm into a light CNC.
The complete parts checklist
For a typical Arduino-driven 4-DOF arm:
- 4–6 servo motors (mix of MG996R and SG90)
- Arduino-compatible board
- PCA9685 servo driver
- 5–6V power supply (sized for stall current)
- Frame (printed, cut or kit) + fasteners
- Gripper + gripper servo
- Jumper wires + breadboard
- 1000µF capacitor across the servo power rail
- Soldering iron and basic tools
Where to go next
With the parts understood, the how to build a robotic arm pillar walks the whole build end to end, robotic arm design covers sizing your own geometry, and the wiring diagram shows exactly how the components connect. If you’d rather buy the components as a matched set, a robotic arm kit bundles most of this list into one box. Browse all parts by category in the shop.
Frequently asked questions
What parts do you need to build a robotic arm?
A DIY robotic arm needs six core parts: actuators (usually hobby servo motors, one per joint), a controller (an Arduino or Raspberry Pi), a servo driver (a PCA9685 for arms with more than a few servos), a separate power supply for the servos, a structure or frame (3D-printed, laser-cut or a kit), and an end effector (a gripper). Add wiring, fasteners and a few tools and that's the complete list.
What are the main components of a robotic arm?
The main components are the links and joints (the structure), the actuators that move each joint (servos or steppers), the controller that runs the code, the drive electronics (servo driver and power supply), the sensors that provide position feedback, and the end effector that does the work. Every robotic arm — hobby or industrial — is built from these same component groups.
How much do robotic arm parts cost?
A basic Arduino-and-servo parts list costs roughly $25–$60: about $12 for a 4-pack of servos, $15 for an Arduino-compatible board, $7 for a PCA9685 driver, plus power supply, wiring and fasteners. A full 6-DOF build with metal-gear servos and a 3D-printed frame runs $80–$200 depending on servo quality.
What are the drive components of a robotic arm?
The drive components are the parts that produce and control motion: the actuators (servo or stepper motors), the servo driver or stepper drivers that generate the control signals, and the power supply that feeds them. Together these convert commands from the controller into physical joint movement.
What accessories and attachments can you add to a robotic arm?
The most useful robotic arm accessories are alternative end effectors — suction cups, magnetic pickups, three-finger grippers and tool mounts — plus sensors and encoders for position feedback, a camera for vision-guided picking, and limit switches for homing. Because the end effector bolts to the last joint, swapping attachments lets one arm do completely different jobs.