How to draw line weight - Industrial design sketching

How to Draw with Line-Weight

How to draw Line-Weight | Industrial Design Sketching
DRAWING CHALLENGE TIP-A-DAY 8/30

It’s 10 am, I’m in a cafe called: Cafe Ngot. I sketch while drinking a Vietnamese called “Cafe sua da” (Ice coffee with sugar milk). It’s delicious.

Sometimes, drawing in a cafe helps me to concentrate better for longer hours. Does it make the same effect for you?

The cafe plays some loud music, people around me are laughing loud, chatting, clapping… but all these noises become like a “meditation music”. When I get deep concentration when I draw, nothing can disturb me.


Draw with 2 pens (1 thin + 1 thick)

Drawing with multiple pens is optional. If you don’t have these, you can follow this tutorial with a simple ballpoint pen. It will be all fine. : )

How to draw Line-Weight | Artline pen
If you can, try to get a 0.2mm and 0.5mm pen. I note that the nib of this pen looks pretty durable compared to the Stabilo Stylist.

Part 1.1| Bold lines at the opposite of the sun (top-left position)

Drawing bold lines allow you to make your sketch eye-catching. It’s an essential skill for a product designer to convince his audience.

But we can’t add the bold lines randomly, or it may look messy. There is a special technique to decide which lines to bold:

  • Rule 1: Bold the lines/edges that are opposite of the sunlight (coming from the top-left).
How to draw line-weight | basic box

Line-weight helps you:

  • Have a sketch that pops from your paper!
  • Gain charism, personality
  • Bring life to your drawing!
Benefits of line-weight for your sketches

Part 1.2| Practice your pen pressure

A beginner tends to draw with a monoline. For you, as a future designer, you need a palette variation of line-weight.

  • Draw a few hatching with various thickness and darkness to practice your pen pressure sensitivity. (The lighter, the thinner. Vice-versa)
Practice pen pressure

Part 1.3| Bold with dynamism

A common mistake is bold too slowly on top of your drawing.
You try to get a perfect bold line, but it looks amateur.

  • To give it a professional look, and draw with dynamism you need to use the ghost drawing.
  • MIND TRICK: Draw the bold line (on top of the light one) like if you draw it for the first time!
Bold with dynamism for a beautiful line weight

Part 2| The 3 levels of line-weight

Part 2.1| The 3 line-weight size

To master drawing any products designs with line-weight,
you need a minimum of 3 lines thickness:

  • The thin line: for hidden lines and construction lines.
  • The medium line: for the visible lines
  • The thick line: for the “pop lines”
The 3 levels of line-weight
Master these 3 lines and you will gain clarity in your industrial design sketches.

Part 2.2| Practice your pen pressure daily

Draw some circles, hatching, and curves to practice your pen pressure. For now, try to find 3 well distinct level of line-weight drawing:


PART 3| Advance Volume Practice

Start drawing a box, and extrude some parts. To train at this, you can refer to the Cube Mania Challenge. Here is the first video on how to draw hundreds of cubes in perspective easy.

Part 3.1| Sketching exercise

Analyze quickly the overall form, and draw the bold lines one-by-one. You need to practice often, to make it intuitive. Remember, that learning a technique is one thing. But another to practice. So take a paper and a pen, and draw with me. : )

A qualified line to be bold needs to meet these 2 conditions:

Rules 1: Edge at the opposite of the sun.
Rule 2: The line has in contact only 1 surface visible. The other side is empty.

The little “s”: means Surface.
The “0” is an empty surface.

3.2 Add a quick background

An extra TIP is to use a colour marker to add extra colour behind to make you sketch pop!


Great job!
That’s it for today!

I hope you enjoy today tutorial! It is the kind of exercise that will follow all your career. Go through it and you will acquire this sketching skill for life! 🙂

Tell me in the comments what pen,
which brand do you like to draw with?


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About The Author

Chou-Tac

Hello! My name is Chou-Tac. I am a Product Designer from France. If the sketching methods I’ve acquired aid me in my life and in my industrial design career, I believe that they can also help you reach your design goal as a student or professional. My aim to help you all along with your design projects and journey. Anytime, feel free to leave a comment in the blog or send me an email at choutac@thedesignsketchbook.com : )

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