Building these DIY kits happens on your own risk. We can't do support or give a guarantee for correct function, because that depends on your own skills. Be responsible and check the building instructions before you buy. Thank you!

Sadly Bastl announced to discontinue most of their DIY products recently. I guess they will focus on Non-DIY and I am sure there will be interesting products in the future. So here is now the stuff they still make as DIY.


And also have a look at their interesting Midi-Looper and Drum Kastle in our Non-DIY section!

Bastl - Kastle

Kastle (v1.5) is a Mini Modular Synthesizer with a headphone output, 2 in/out ports for interfacing other gear and it runs on batteries. It is DIY friendly and ideal for beginners in modular synthesis, but it will add some quite unique functionality to any modular synthesizer system. It delivers the fun of modular synthesis at a low cost and fits into your pocket so you can play it everywhere! It has a unique digital lo-fi sound and it can be melodic as well as very noisy and drony, soft or harsh. It is designed to be fun on its own but it is most powerful when combined with other modular gear. Kastle is an open source DIY project which runs on two Attiny 85 chips that can be reprogrammed with an Arduino. One chip is dedicated to sound generation while the other one handles modulation. Several firmwares for the Attiny chips are available thru gitHub. Videos here and here.


The v1.5 version combines a complex oscillator and LFO with stepped waveform generator

The oscillator section has 3 sound parameters: PITCH, TIMBRE and WAVESHAPE – all under voltage control and with 6 different synthesis modes. It has a main output and a secondary waveform output. Both can be used independently or in combination. The 3 synthesis modes available thru the main output are: phase modulation, noise mode and track & hold modulation. There are 3 more modes on the secondary OSC output: phase distortion, tonal noise mode and formant synthesis. Each mode utilizes one or two oscillators. The PITCH parameter controls the main oscillator, the TIMBRE sets the PITCH of the modulating oscillator and the WAVESHAPE depends on the synthesis mode.

The voltage controllable LFO has a triangle and square output and a reset input. The stepped waveform generator is inspired by the Rungler circuit by Rob Hordijk. It can produce 8 different voltages either in random order or in 8 or 16 step looping patterns depending on how the BIT IN is patched.



• Triangle core VCO

Complex oscillator

3 synthesis modes on the main output: phase modulation, noise mode, track & hold modulation

3 more modes on the secondary OSC output: phase distortion, tonal noise mode, formant synthesis

PITCH control with offset and CV input with attenuator

TIMBRE control with offset and CV input with attenuator

WAVESHAPE control with offset and CV input

Voltage controllable LFO with triangle and square outputs and reset input

Stepped voltage generator with random, 8 step and 16 step loop mode

2 I/O CV ports that can be routed to any patch point

Main output can drive headphones

Open source

possibility of exchanging different LFO and OSC chips


Technical details

Dimensions: 70 x 60 x 50 mm

3x AA battery operation or USB power selectable by a switch

• Mini patch cables included


This is a Do-It-Yourself kit, not an assembled module. Building instructions can be found here.

DIY level: easy.

Bastl - Kastle

99,00 €

  • 0,11 kg
  • Available
  • Ships within 3-5 days1

Bastl - Noise Square

We found a single Noise Square left. Bastl have discontinued most of their DIY products, so this is the last chance. We blow it out as an easter special! No further info here...


This is a Do-It-Yourself kit, not an assembled module. Building instructions can be found here.

DIY level: medium.

Bastl - Noise Square
96,00 €

85,00 €

  • 0,13 kg
  • Sold out at the moment

Bastl - Microgranny

MicroGranny 2 is a monophonic granular sampler. It reads wav samples from microSD card and applies granular algorithms to them. You can also adjust start, end, sample rate (tuned or free run), crush and envelope (attack release). MIDI Input allows external control of all parameters as well as transposition of the samples, or playing individual grains by different keys. For Soundbanks, Midi Implementation chart and source codes and update history please visit the Bastl website.



• Monophonic mono sampler
• MicroSD card (storing + recording samples, storing presets)
• 6 sounds with full adjustments storable in a preset at once
• 60 presets in 10 banks (6 preset per bank), stored as .txt files on microSD card
• WAV sample playback from microSD card (mono, 22050 Hz, 8 or 16 bit, two letter file name)
• 8-bit 22050Hz wav recording via line input or onboard microphone
• Hold button
• Sample rate (tuned or free run)
• Crush
• Start, end position with repeat, instant loop
• Granular settings: grain size and shift speed (positive or negative)
• Amplitude envelope attack and release
• MIDI Input – responds to note, cc and clock (synchronize loop and grains)
• MIDI side chain envelope restart
• Input & output volume knob
• Power switch – plug / battery
• Hackable – Arduino based


Technical details

• Dimensions: 140 x 75 x 55 mm
• Powered by 9V battery or 9V DC supply (center positive)

• Color: Laguna (light blue box).


This is a Do-It-Yourself kit, not an assembled module. Building instructions can be found here.

DIY level: easy.

Bastl - Microgranny

167,00 €

  • 0,33 kg
  • Sold out at the moment

Bastl - Kompas

Probability Trigger Generator. Kompas is a three-coordinate probabilistic pattern navigator. Each coordinate has a unique travelling pace and a dedicated trigger output. The amount of probability can be adjusted manually or by external voltages. Once a coordinate has been adjusted, a new pattern is generated and looped until the next change of direction. This tool is the outcome of the environment we are in and is inspired by non-linear approach to music and life – don't build any expectations, choose your direction and discover new paths. Unlike common probability operation, instead of filtering a pre-determined sequence, Kompas uses probability to generate new looping patterns based on the direction you choose. Here is a video about Kompas.



global clock and reset input

3 x 32 step pattern generators with travelling algorithms

3 CV inputs for coordinate modulation

3 trigger outputs

2/5/10ms selectable trigger length (via boot settings)

5ms default trigger length

5V trigger outputs

0-5V protected CV inputs

60Hz maximum clock rate (3600 BPM)


Technical details

• 5HP

• 35 mm deep

• Alu panel

• 30mA @+12V, 0mA @-12V


This is a Do-It-Yourself kit, not an assembled module. Building instructions can be found here. Firmware and schematics via Github.

DIY level: medium.

Bastl - Kompas
128,50 €

115,00 €

  • 0,11 kg
  • Available
  • Ships within 3-5 days1