This is a list of synthesizers and related hardware you can build on your own. All designs are open-source including firmware. Submit designs which is not in list and discuss your building experience.

1. ATtiny Punk Console — ATtiny85 implementation of Atari Punk Console
2. Aciduino — Roland TB-303 step sequencer clone aimed for live interaction
3. Ambika — Multi-voice, hybrid synthesizer. Descendant of Shruthi.
4. Anushri — Analog monosynth with a lo-fi digital drums
5. ArduTouch — Arduino-compatible music synthesizer
6. Arpie — Compact, highly-functional, MIDI arpeggiator
7. BE2N — Full-fledged voice module with two specular Benjolins at its core
8. Beam Catcher — Analog light-based synthesizer
9. Coron DS7 (DS8) — Percussion & drum synth
10. Drone & Drama — Simple Teensy-based drone synth
11. DrumKid — Lo-fi aleatoric Arduino drum machine
12. Echo Rockit — Compact synth/effect processor
13. Faderbank 16n — 16 faders MIDI-controller compatible with modular world
14. Fasma Festival — Yet another Teensy drum machine with clock sync
15. Flounder — Teensy based USB midi keyboard + controls + stereo audio
16. Hog — Double-voice analog monophonic synthesizer with two oscillators
17. Hypjolin — Cross-modulating ultra-chaos generator
18. Kelpie — Portable polyphonic digital synthesizer
19. LMN-3 — OP-1 inspired DAW-in-a-box
20. Le Strum — Compact and simple yet funny MIDI strummer
21. Lil' mono — Simple east-coast style analog synthesizer
22. Lunchbeat — 1-bit percussion sounds and a sequencer
23. MIDIvampire II — 4 voice drum machine that is powered from the MIDI data line
24. Matrix sequencer — Standalone MIDI sequencer
25. Meeblip Micro — Hackable monophonic synth
26. Meeblip SE — Hackable monophonic synth
27. Meeblip Triode — Hackable monophonic synth based on ATmega32
28. Mega MIDI — MIDI-compatible Sega Genesis/Megadrive synthesizer with real sound chips
29. Mini Dexed — FM synthesizer closely modeled on the famous DX7
30. Mixtape Alpha — Credit-card sized ATmega328 4 voice synth
31. Mushsynth-8 — 8-voice polyphonic drone synth with a touch keyboard
32. N32B — Hi-res macro MIDI controller
33. NSynth Super — An experimental physical interface for the NSynth AI algorithm
34. NTH synth — 8-bit hackable mono synth
35. Nano minipops — Korg Minipops drum machine made around Arduino
36. Noise Toaster — Simple, full analog noise synth
37. NoiseLab — Analog noise synthesizer
38. Norns shield — Dynamic instrument, creation platform and musical computer
39. OTTO — Digital groovebox with synths, looper, samplers, effects and a sequencer
40. OpenDeck — Platform for ultimate MIDI control deck building
41. Overcycler — Polyphonic hybrid single cycle / analog synthesizer
42. POLY555 — Polyphonic, analog, square wave synth based on the 555 timer
43. Paper Bits — Small, modular synthesizer system. Voltage controlled, stripboard compatible.
44. PicoTracker — Low cost music tracker platform
45. Plinky — 8-voice polyphonic touch synthesizer that specializes in fragile, melancholic sounds
46. Polaron — Digital drum machine based on Teensy 3
47. Polykit X1 — Full analog, semi modular synthesizer
48. Portable synth — OP-1 style portable groovebox based on Teensy 4
49. PreenFM 2 — Beloved old FM synthesis in small, modern DIY box
50. Protean — ATtiny-based motion texture source
51. Quantum DJ — Electromagnetic noise to 1-bit sound converter
52. Real SID shield — Digital interface to SID chip of Commodore 64
53. S54 Liv's Synth — Hybrid mono synth with full analogue signal path
54. SC1000 — Portable digital scratch instrument
55. Shruthi — Hybrid synth with digital generators and swappable analog filter boards
56. Sound Lab Mini-Synth MkII — Full analog descendant of Sound Lab Mini-Synth
57. Sound Lab Mini-Synth — Full analog legendary MFOS design
58. Teensy Audio FX — Playable effects modeled on the Teenage Engineering PO series
59. Teensy Beats Shield — Handheld audio sequencer in PO style
60. Totoro — Cheap and easy to solder 2 oscillators synth on single IC
61. WTPA2 (Where is the party at 2) — 8-bit audio sampler kit
62. Wee Noise Maker — Pocket size sampler/sequencer with DAC, headphone amplifier and audio input
63. Wirehead Freaq FM — Dual-voice, 2 operator 8-bit FM Arduino Synth in Volca form-factor
64. Wirehead Mutant — 8-bit, 2-oscillator subtractive Arduino synth for generative techno in Volca form-factor
65. YM2149 Synth — Little chip that was used in various retro arcade machines and consoles now ready to serve
66. Yowler — Compact and versatile noise/drone synth
67. ZeKit — 4 voice paraphonic synth
68. Zynthian — Open platform for sound synthesis & processing
69. x0x heart — Heart of the Roland TB-303, surgically extracted to be transplanted into your designs
70. x0xb0x — Full reproduction of the original Roland TB-303 synthesizer, with fully functional sequencer

upd: 2025-03-27