I have a lot of free time on my hand right now. I only need four hours sleep. I got time to burn on flights of fancy.
I frequently use my 2 mm Muli-8 clutch pencils. They are plasticky and cheap as chips but awfully useful. They usually come with 7 colored leads, including a non-copy blue one for safety, and one graphite lead. They also have colored ballpoint pen inserts that fit this pen. You can configure the pen to your liking but with 8 choices finding the right lead gets a little tedious.
I made a custom lead indicator for one of my Multi-8 pens. At first I was going to either leaser-engrave or etch the markings into thin sheet steel before forming int into a sleeve. Then I decided that for a cheap plastic pencil this would be overkill and I fabricated a plastic lead indicator band.
Home-fabricated lead/pen refill indicator installed. The lead or pen is chosen by twisting the clip to the corresponding marking and releasing the pen clutch by pressing the rear button. My configuration gives me a red and a blue 0.7mm pen, 8B, 4B, 2B, B, HB, and H graphite lead for drawing, technical drawing, and writing. If I so desire I can swap the two ballpoint leads out for 2H and 4H, a highlighter, or a 2mm silver point, etc.
Red and Blue contain colored led refills at this time but I have red and blue ballpoint pen insert on order.
The pocket clip is the lead/pen selector The indicator band is a ring-shaped piece of thin plastic that is friction fit.
Next on my to-do list is eating pie.