Parametric Pipe Adapter (OpenSCAD)

You can use this to make an adapter to join two pipes together. You can define many parameters so it is easy to get right:

// Basic Parameters
First_pipe_outer_diameter = 30;
First_pipe_inner_diameter = 28;
Second_pipe_outer_diameter = 25;
Second_pipe_inner_diameter = 20;

// Advanced Parameters
Minimum_wall_thickness = 2; // The minimum thickness wall your printer can do.
Printer_x_y_tolerance = 0.00; // Tolerance space on either side for the tube
Extra_inner_length = 5; // Distance the inside of the tube adapter extends so you can tie something around the pipe to keep it on.
Separation = 0; // Zero means twice the minimum width
Quality = 5; // Proportional to the overall diameter of the object.