diff --git a/builders b/builders
new file mode 100644
index 0000000..5246b7d
--- /dev/null
+++ b/builders
@@ -0,0 +1 @@
+ssh://nixremote@seras.kyouma.net x86_64-linux,aarch64-linux - 40 2 nixos-test,benchmark,big-parallel,kvm
diff --git a/config/common/default.nix b/config/common/default.nix
index ef26bbd..7241741 100644
--- a/config/common/default.nix
+++ b/config/common/default.nix
@@ -57,8 +57,15 @@ with lib; {
   nix.gc.automatic = true;
   nix.gc.options = "--delete-older-than 7d";
   nix.optimise.automatic = true;
+  nix.registry.nixpkgs.to = {
+    type = "path";
+    path = pkgs.path;
+  };
   nix.settings.experimental-features = [ "nix-command" "flakes" ];
   nix.settings.trusted-users = [ "root" "@wheel" ];
+  nix.extraOptions = ''
+	  builders-use-substitutes = true
+	'';
 
   nixpkgs.config.allowUnfree = true;
 
diff --git a/config/hosts/lain/configuration.nix b/config/hosts/lain/configuration.nix
index e1799d7..f5d6c7d 100644
--- a/config/hosts/lain/configuration.nix
+++ b/config/hosts/lain/configuration.nix
@@ -1,52 +1,27 @@
 { config, inputs, lib, pkgs, ... }: {
   imports = [
-    inputs.nixos-hardware.nixosModules.raspberry-pi-4
     ../../common
+    ../../profiles/remote-builder.nix
+    ../../profiles/rpi.nix
     ../../profiles/headless.nix
   ];
 
-  boot.loader.efi.canTouchEfiVariables = true;
-  console.enable = false;
-
   deployment = {
-    targetHost = "192.168.178.166";
-    targetUser = "nixos";
+    targetHost = "192.168.178.171";
   };
 
-  environment.systemPackages = with pkgs; [
-		kodiPackages.jellyfin
-		kodiPackages.keymap
-    libcec
-    libraspberrypi
-    raspberrypi-eeprom
-  ];
-  fileSystems = {
-    "/" = {
-      device = "/dev/disk/by-label/NIXOS_SD";
-      fsType = "ext4";
-      options = [ "noatime" ];
-    };
-  }; 
-  hardware = {
-    bluetooth.enable = true;
-    deviceTree.enable = true;
-    raspberry-pi."4" = {
-      audio.enable = false;
-      apply-overlays-dtmerge.enable = true;
-      fkms-3d.enable = true;
-    };
+  networking = {
+    hostName = "lain";
+    dhcpcd.enable = lib.mkForce true;
+    networkmanager.enable = true;
+    useDHCP = lib.mkForce true;
   };
-
-  kyouma.machine-type.physical = true;
+  systemd.network.enable = lib.mkForce false;
 
   nixpkgs.overlays = [
-    (self: super: { libcec = super.libcec.override { withLibraspberrypi = true; }; })
+    (self: super: { kodi-wayland = super.kodi-wayland.overrideAttrs { doInstallCheck = false; }; })
   ];
 
-  networking.hostName = "lain";
-  networking.networkmanager.enable = true;
-  systemd.network.enable = lib.mkForce false;
-
   systemd.sockets."cec-client" = {
     after = [ "dev-vchiq.device" ];
     bindsTo = [ "dev-vchiq.device" ];
@@ -70,30 +45,22 @@
     };
   };
 
-  services.avahi = {
-    enable = true;
-    ipv6 = true;
-    nssmdns4 = true;
-    publish.enable = true;
-    publish.userServices = true;
-  };
   services.cage = {
     enable = true;
+    environment = {
+      WLR_NO_HARDWARE_CURSORS = "1";
+    };
     program = "${pkgs.kodi-wayland}/bin/kodi-standalone";
     user = "kodi";
   };
-  services.fstrim.enable = true;
-  services.pipewire = {
-    enable = true;
-    alsa.enable = true;
-    pulse.enable = true;
-  };
   services.udev.extraRules = ''
     # allow access to raspi cec device for video group (and optionally register it as a systemd device, used below)
     KERNEL=="vchiq", GROUP="video", MODE="0660", TAG+="systemd", ENV{SYSTEMD_ALIAS}="/dev/vchiq"
   '';
 
-  users.mutableUsers = lib.mkForce true;
-  users.users.kodi.extraGroups = [ "video" ];
-  users.extraUsers.kodi.isNormalUser = true;
+  users = {
+    mutableUsers = lib.mkForce true;
+    users.kodi.extraGroups = [ "video" ];
+    extraUsers.kodi.isNormalUser = true;
+  };
 }
diff --git a/config/hosts/ryuuko/configuration.nix b/config/hosts/ryuuko/configuration.nix
index 4995bb9..cf3e802 100644
--- a/config/hosts/ryuuko/configuration.nix
+++ b/config/hosts/ryuuko/configuration.nix
@@ -3,11 +3,12 @@
     inputs.nixos-hardware.nixosModules.lenovo-thinkpad-x1-extreme-gen4
     ../../common
     ../../profiles/graphical
+    ../../profiles/remote-build.nix
     ./hardware-configuration.nix
     ./disko.nix
   ];
 
-  boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
+  #boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
   boot.extraModprobeConfig = ''
     options i915 enable_guc=3
   '';
diff --git a/config/hosts/seras/configuration.nix b/config/hosts/seras/configuration.nix
new file mode 100644
index 0000000..28d7699
--- /dev/null
+++ b/config/hosts/seras/configuration.nix
@@ -0,0 +1,35 @@
+{ config, inputs, lib, pkgs, ... }: { 
+  imports = [
+    ../../common
+    ../../profiles/headless.nix
+    ../../profiles/kartoffel.nix
+    ../../profiles/lxc.nix
+  ];
+
+  boot.binfmt.emulatedSystems = ["aarch64-linux"];
+
+  deployment.targetUser = "emily";
+
+  networking = {
+    hostName = "seras";
+    nftables.enable = lib.mkForce false;
+  };
+  nix.settings.trusted-users = [ "nixremote" ];
+  nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
+
+  systemd.network.networks."98-eth-default" = {
+    address = [
+      "2a0f:be01:0:100::169/128" 
+    ];
+  };
+  users.users.nixremote = {
+    isNormalUser = true;
+    shell = pkgs.fish;
+    ignoreShellProgramCheck = true;
+    openssh.authorizedKeys.keys = [
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIA/+iN407+HsfHbbC3tfdA8Yf4TZ08qXQMb4tb/SDAs+ emily@card"
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICT0dGyLUjxFnvqUmex+5xUGQ7D4yGHKo267JgApcq0k root@ryuuko"
+      "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIDTwCSWYODyvTJxwB6Rahuy0j6s/YYwtQta8bjzG/We root@ryuuko-arch"
+    ];
+  };
+}
diff --git a/config/profiles/remote-build.nix b/config/profiles/remote-build.nix
new file mode 100644
index 0000000..1b8e134
--- /dev/null
+++ b/config/profiles/remote-build.nix
@@ -0,0 +1,11 @@
+{config, lib, pkgs, ... }: {
+  nix.buildMachines = [{
+    hostName = "seras.kyouma.net";
+    sshUser = "nixremote";
+    maxJobs = 40;
+    speedFactor = 5;
+    systems = [ "aarch64-linux" "x86_64-linux" ];
+    supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
+  }];
+  nix.distributedBuilds = true;
+}
diff --git a/config/profiles/rpi.nix b/config/profiles/rpi.nix
new file mode 100644
index 0000000..71cb6c5
--- /dev/null
+++ b/config/profiles/rpi.nix
@@ -0,0 +1,81 @@
+{ config, inputs, lib, pkgs, ... }: {
+  imports = [
+    inputs.nixos-hardware.nixosModules.raspberry-pi-4
+  ];
+  kyouma.machine-type.physical = true;
+
+  boot = {
+    extraModprobeConfig = ''
+      options snd_bcm2835 enable_headphones=1
+    '';
+    kernelParams = [ "snd_bcm2835.enable_hdmi=1" ];
+    loader.raspberryPi.firmwareConfig = ''
+      dtparam=audio=on
+      dtparam=krnbt=on
+    '';
+  };
+  console.enable = false;
+
+  documentation.man.generateCaches = false;
+
+  environment.systemPackages = with pkgs; [
+    bluez
+    bluez-tools
+    libcec
+    libraspberrypi
+    raspberrypi-eeprom
+  ];
+  fileSystems = {
+    "/" = {
+      device = "/dev/disk/by-label/NIXOS_SD";
+      fsType = "ext4";
+      options = [ "noatime" ];
+    };
+  }; 
+  hardware = {
+    bluetooth.enable = true;
+    pulseaudio.enable = true;
+    deviceTree = {
+      enable = true;
+      overlays = [
+        {
+          name = "bluetooth-overlay";
+          dtsText = ''
+            /dts-v1/;
+            /plugin/;
+            
+            / {
+                compatible = "brcm,bcm2711";
+            
+                fragment@0 {
+                    target = <&uart0_pins>;
+                    __overlay__ {
+                            brcm,pins = <30 31 32 33>;
+                            brcm,pull = <2 0 0 2>;
+                    };
+                };
+            };
+          '';
+        }
+      ];
+    };
+    raspberry-pi."4" = {
+      apply-overlays-dtmerge.enable = true;
+      fkms-3d.enable = true;
+    };
+  };
+
+  nixpkgs.overlays = [
+    (self: super: { libcec = super.libcec.override { withLibraspberrypi = true; }; })
+  ];
+
+  sound.enable = true;
+  services.avahi = {
+    enable = true;
+    ipv6 = true;
+    nssmdns4 = true;
+    publish.enable = true;
+    publish.userServices = true;
+  };
+  services.fstrim.enable = true;
+}
diff --git a/flake.nix b/flake.nix
index 128e9fb..dfba0a6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -21,15 +21,21 @@
     };
   };
 
+  nixConfig = {
+    builders-use-substitutes = true;
+    builders = "ssh://nixremote@seras.kyouma.net x86_64-linux,aarch64-linux - 40 2 nixos-test,benchmark,big-parallel,kvm";
+  };
+
   outputs = { self, nixpkgs, flake-utils, ... }@inputs: {
     colmena = let
-      hosts = [ "web-dus" "crime" "ryuuko" "lain" ];
+      hosts = [ "web-dus" "crime" "ryuuko" "lain" "seras" ];
       hostCfg = hostname: {
         imports = [ (./config/hosts/${hostname}/configuration.nix) ];
       };
     in {
       meta = {
         allowApplyAll = false;
+        machinesFile = ./builders;
         nixpkgs = nixpkgs.legacyPackages.x86_64-linux;
         nodeNixpkgs = {
           lain = nixpkgs.legacyPackages.aarch64-linux;