From 7a76502453caa1d6ae3060ebd385d8588061fc9b Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Tue, 7 Apr 2026 00:40:29 +0300
Subject: [PATCH] make an equivalent OpenSCAD tube model

---
 mini-tube.scad | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 mini-tube.scad

diff --git a/mini-tube.scad b/mini-tube.scad
new file mode 100644
index 0000000..9b186c5
--- /dev/null
+++ b/mini-tube.scad
@@ -0,0 +1,40 @@
+$fa = $preview ? 5 : 1;
+$fs = $preview ? 0.1 : 0.01;
+
+volume_ml = 5;
+cross_section_mm2 = 100;
+marks = [[1, 30], [.2, 15]];
+
+extra_height_mm = 5;
+wall_thickness_mm = 0.8;
+mark_depth_mm = 0.3;
+mark_width_mm = 0.4;
+
+bottom_thickness_mm = wall_thickness_mm;
+
+cross_section_cm2 = cross_section_mm2 / 100;
+useful_height_cm = volume_ml / cross_section_cm2;
+
+inner_radius_mm = 10 * sqrt(cross_section_cm2 / PI);
+outer_radius_mm = inner_radius_mm + wall_thickness_mm;
+
+inner_height_mm = 10 * useful_height_cm + extra_height_mm;
+outer_height_mm = inner_height_mm + bottom_thickness_mm;
+
+difference() {
+	// outer shape
+	translate([0, 0, -bottom_thickness_mm])
+	cylinder(h=outer_height_mm, r=outer_radius_mm);
+
+	// inner shape
+	cylinder(h=inner_height_mm + 1, r=inner_radius_mm);
+
+	// marks
+	for (m = marks)
+	let (step_ml = m[0], angle = m[1])
+	rotate_extrude(angle=angle)
+	translate([outer_radius_mm - mark_depth_mm, 0, 0])
+	for (v = [0:step_ml:volume_ml])
+	translate([0, 10 * v / cross_section_cm2, 0])
+	square([mark_depth_mm + 1, mark_width_mm]);
+}