diff --git a/.gitmodules b/.gitmodules
index 8e4d20d..bd1cf08 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "scad/common"]
 	path = scad/common
 	url = https://git.sixteenmillimeter.com/modules/common.git
+[submodule "scad/knobs"]
+	path = scad/knobs
+	url = https://git.sixteenmillimeter.com/modules/knobs.git
diff --git a/scad/bolex_matte_box.scad b/scad/bolex_matte_box.scad
index 285575a..b44ca3b 100644
--- a/scad/bolex_matte_box.scad
+++ b/scad/bolex_matte_box.scad
@@ -2,12 +2,72 @@ use <./common/common.scad>;
 
 RAIL_SPACING_HALF_IN = 30;
 HALF_IN_RAIL_D = 13;
+ATTACH_H = 20;
+INDEX_CARD_X = 127;
+INDEX_CARD_Y = 76.2;
+INDEX_CARD_43 = (INDEX_CARD_Y / 3) * 4;
 
-module bolex_matte_box () {
+module bolex_matte_box_rails_attach (pos = [0, 0, 0]) {
 	$fn = 100;
 
-	translate([RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D), h = 50, center = true);
-	translate([-RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D), h = 50, center = true);
+	translate(pos) translate([0, 0, ATTACH_H / 2]) difference () {
+		union () {
+			translate([RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D) + 3, h = ATTACH_H, center = true);
+			translate([-RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D) + 3, h = ATTACH_H, center = true);
+			cube([RAIL_SPACING_HALF_IN, HALF_IN_RAIL_D + 6, ATTACH_H], center = true);
+		}
+
+		translate([RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D) + 0.3, h = ATTACH_H + 1, center = true);
+		translate([-RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D) + 0.3, h = ATTACH_H + 1, center = true);
+		cube([RAIL_SPACING_HALF_IN, 2, ATTACH_H + 1], center = true);
+		//m4 bolt
+		translate([0, ((HALF_IN_RAIL_D + 6) / 2) + 4, 2]) rotate([90, 0, 0]) {
+			m4_nut(HALF_IN_RAIL_D + 6);
+			cylinder(r = R(4.25), h = 200, center = true, $fn = 50);
+		}
+	}
 }
 
-bolex_matte_box();
\ No newline at end of file
+module bolex_matte_box_rails_cap (pos = [0, 0, 0]) {
+	$fn = 100;
+
+	translate(pos) translate([0, 0, ATTACH_H / 2]) difference () {
+		union () {
+			translate([RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D) + 3, h = 20, center = true);
+			translate([-RAIL_SPACING_HALF_IN / 2, 0, 0]) cylinder(r = R(HALF_IN_RAIL_D) + 3, h = 20, center = true);
+			cube([RAIL_SPACING_HALF_IN, HALF_IN_RAIL_D + 6, ATTACH_H], center = true);
+		}
+
+		translate([RAIL_SPACING_HALF_IN / 2, 0, 4]) cylinder(r = R(HALF_IN_RAIL_D), h = 20, center = true);
+		translate([-RAIL_SPACING_HALF_IN / 2, 0, 4]) cylinder(r = R(HALF_IN_RAIL_D), h = 20, center = true);
+	}
+}
+
+module matte_box (pos = [0, 0, 0]) {
+	translate(pos) {
+		translate([0, 0, 8 / 2]) difference () {
+			rounded_cube([INDEX_CARD_43, INDEX_CARD_Y + 8,  8], d = 5, $fn = 40, center = true);
+			cube([INDEX_CARD_43 - 12, INDEX_CARD_Y - 4,  8 + 1], center = true);
+			translate([2, 0, 0]) cube([INDEX_CARD_43, INDEX_CARD_Y + 1,  1.5], center = true);
+		}
+		translate([0, 0, (10 / 2) + (20 / 2)]) difference () {
+			rounded_cube([INDEX_CARD_43, INDEX_CARD_Y + 8,  20],  d = 5, $fn = 40, center = true);
+			rounded_cube([INDEX_CARD_43 - 4, INDEX_CARD_Y + 8 - 4,  20 + 1],  d = 5, $fn = 40, center = true);
+		} 
+	}
+}
+
+module bolex_matte_box () {
+	BASE_Y = 100;
+	BASE_DIST = BASE_Y - ((INDEX_CARD_Y + 8) / 2);
+	bolex_matte_box_rails_attach([0, -BASE_Y, 0]);
+	translate([0, (-BASE_DIST / 2) - ((INDEX_CARD_Y + 8) / 2)  + 4, 8 / 2]) {
+		cube([20, BASE_DIST - 2, 8], center = true);
+		translate([6, 0, 6]) cube([3, BASE_DIST - 4, 20], center = true); 
+		translate([-6, 0, 6]) cube([3, BASE_DIST - 4, 20], center = true); 
+	}
+	matte_box();
+}
+
+bolex_matte_box();
+//rotate([-90, 0, 0]) import("../bolex_matte_box-4x5.5_cards.stl");
\ No newline at end of file
diff --git a/scad/knobs b/scad/knobs
new file mode 160000
index 0000000..e0bfb8b
--- /dev/null
+++ b/scad/knobs
@@ -0,0 +1 @@
+Subproject commit e0bfb8b57f7e2fc0c1039c312f77de35410c9b5c