I would like to design a modular system oriented techno hardcore. I already own the make noise 0-coast, Math, Plait, Veils and Links from Mutable Instrument. If you have any advice of additional modules...
Thank you

have you seen the mylarmelodies video on how to build a small techno system on YouTube???

Utility modules are the inexpensive, dull polish that makes the expensive, shiny modules actually shine!!!

sound sources < sound modifiers < modulation sources < utilities

Here are some tips:

1/ get an Intellijel 7u case
2/ Endorphin.es Queen of Pentacles, Black Noire, or VPME Quad Drum for percussion
3/ Quad VCA from Intellijel
4/ Winter Eloquencer sequencer- thank me later
5/ Instruo Divkid 0chd for modulation
6/ Happy Nerding FX Aid for effects
7/ Intellijel Quadrax with expander for creative envelope generator
8/ Intellijel 1u Quadratt for mixer/attenuator/attenuverter

That will get you in the ballpark.

My experience: buy a decent drum machine/sampler and focus your modular for a specific task rather than viewing it as a jack of all trades.

Well, let's see...
ModularGrid Rack
Went with sacguy's case suggestion. This uses a 7U x 104 hp Intellijel cab. And because of that, your MIDI, inputs, and outputs can go to the cab's built-in jacks, making things a bit less chaotic.

ROW: Audio in on the right. Then there's the MIDI interface, followed by Intellijel's Noise Tools tile for master clocking, sample-and-hold, noise, and the like. The QuadrATT next to that gives you an extra set of attenuverters, DC-coupled mixing for CV/mod signals, or as a mixer for audio. The little black tile after it is a Takaab dual LPG so that you can have that to add percussives, and that's followed by an Intellijel Stereo VCA for CV control over output levels. And then the output tile is right after that.

TOP: Plaits. Then the VCO next to it is a NANO Ona, which gives you a voicing akin to the SH-101 and its suboscillator. Then the Schlappi Angle Grinder is a VCO/processor that's got a nasty, distorted sound that really lends itself to hard acid tracks. And if that's not enough crazy timbral fun, I put in a Joranalogue FLD6 which is a six-stage wavefolder that can take two VCOs on its own (or one Plaits if you use the AUX out). Veils follows to allow VCA control over four audio sources, then the matching VCF for the Ona by G-Storm. The other VCF is also G-Storm's doing, a module based on the SSM filters in Korg's Delta and their Poly 61. The Doepfer stereo mixer then lets you control levels out of the filters as well as setting up a stereo signal for the Beads, which is Mutable's follow-up to their Clouds module. Then the Stasis Leak and the Purrtronics Purrvrrb both have the mono-in/stereo-out architecture for pairing with the Tex-Mix's AUX send/returns.

BOTTOM: The little sliver to the left is one of Konstant Labs' PWRchekrs so that you can easily keep an eye on your DC rail health. Then there's the Pam's, and that's followed by Doepfer's little quad LFO so that you have some free-running LFOs to add in with the rest of the mod sources. The CVable LFOs are in the 4ms Quad Pingable LFO, meaning that they can be "tap clocked" by hand or by another trig/gate, and they have ridiculously LONG wave cycle times, the sort of thing that you could use one cycle that's the length of one track to do some "global modulation". Then there's a Maths, and my fave little modulation manipulation core, a Frap 321 mixer/attenuverter/DC offset source and a Happy Nerding 3xVCA. Those allow you to take existing modulation signals and combine them in some rather elaborate ways that can go beyond typical setups that have no such manipulation core. I put in a Quadrax/Qx for more generally-unusual modulation sources beyond the typical envelope generator. A Doepfer Dual ASDR after that gives two "normal" ADSR envelopes. And lastly, the Tex-Mix...this has four mono input channels along with the Tex-Mix master. The Tex-Mix is something I picked up on thanks to Jim...and if you're happy about having just VCA control over the input levels, this will be perfect. And as mentioned earlier, the Tex-Mix has the mono send/stereo returns that both the Stasis Leak and Purrvrrb like to see. It also has your headphone preamp for quiet practicing.

I used my past experiences in the 1990s rave scene to cook this one up. The ability to mangle any or all of the VCO sources also pushes that acid direction really heavily, for one thing. Plus, this is set up with "subsystems" like the modulation manipulation core, so no one module has to do everything on its own.

Now, as for the 0-Coast...what I would suggest is to get the 0-Ctrl and the Strega, then combine them into a stand like this: https://reverb.com/item/39263230-3dwaves-triple-tier-stands-for-the-make-noise-0-coast-0-ctrl-strega-semi-modular-synthesizers That way, you can treat them as a single instrument that can also be crossconnected with the Eurorack and which costs way less than anything else with the word "Easel" in the name. Sounds like a real great deal, IMHO!