New to Grasshopper

Hi all.

I want to learn to use Grasshopper, specifically, start with a footstool, as shown. I then want to be able to change things like length, width, height, and also dimensions of parts in the piece.

It’s probably ages worth of learning, but even if I could start with something like how to draw, say a board 2 feet long 1 by 4 and be able to change it to a 3 foot long 2 by 6.

I started looking at David Ruttens Grasshopper tutorials (1-4 of 13), but am getting restless and feel like my needs are simpler.

Draw it in Rhino first… Then you will probably be able to figure out how to do it in GH afterwards.

But it depends on if you want to do it the “hard” way by defining everything in GH.
Or if you have a Rhino drawing and want to modify that in GH, which would be the “easy” way…

When it comes to production of a bespoke piece of furniture using CNC and such, it nice to be able to fine tune things like precise material thicknesses in GH instead of in a Rhino drawing.
But if you have one product which you want to make into a “parametric” model also consider feature-based CAD system like “fusion 360” or solidWorks, inventor etc.

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I would start something like this, drawing four corner posts, then adding more details. Slider dimensions are in inches.


footstool_2025Jan17a.gh (7.1 KB)

There’s a handful of ways you could do that; how you do it will vary based on your use situation, but a couple options that first come to mind:

Option 1: Use a Center Box component. Note that each of the X, Y, and Z inputs have an equation in them, dividing the input by 2. This has to be done due to the way the Center Box component works.

Option 2: Draw a rectangle, and extrude it, then cap it. Note that I’ve included a pair of Construct Domain components that create a domain from -width/2 to width/2 (and the same for height), due to the input expected by the rectangle. This creates a rectangle centered on the plane’s zero point.

There’s probably a dozen other ways to put a simple board together, depending on how you want to use it, where you want the origin point to be, whether it’s between two other pieces like the stretchers on your footstool…

It’s not ages of learning though. Work through some tutorials, check some Youtube videos, see how other people have done it before you. Learn how parameter inputs work, learn how basic drawing geometry works, etc. Build easy things, then stretch out to build more interesting things. You get a sense pretty quickly of how to think in a way to make things flexible.
Carl Board.gh (11.3 KB)

For the wood parts you can do it with GH fairly easily using GH components. You need to create rectangular solids for the 4 legs, horizontal spreaders, and vertical supports. That’s actually only 4 different parts. Once you have these you have to position them in the right places.
boxes.gh (6.4 KB)

Here’s a little GH file that does what I just wrote:

GH has the Box Rectangle and Box components in the menu Surface/Primitive section. Either of these will work for making 3D boxes. Be aware that you have to specify the correct plan on which the box will be built. That’s the easiest way to get the boxes in the correct orientation.

Use the Move component along with X, Y, Z unit vectors and/or the 3D vector component to move the boxes to the correct locations.

The cushion is a separate piece and it’s not clear how it is supported. Probably some horizontal slats like the vertical pieces would work OK.

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There is no single correct way. Here is a different method using two Mirror components.


footstool_2025Jan17b.gh (8.1 KB)

The expression on ‘X’ and ‘Y’ inputs of Pt is “x / 2”.

On and on it goes…


footstool_2025Jan18a.gh (16.5 KB)

Too complicated?

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I don’t think @Carl_Mesrobian will learn much about GH from that image.

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I don’t believe it either.
It is just to stimulate the use of GH.

If one believes that was done using GH…? But it could have been done with Rhino, so shows nothing relevant to learning GH, in my humble opinion.

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https://discourse.mcneel.com/search?q=wood%20joint

I played around with “footstool-2025Jan17b”?? The one with just the legs…

Definitely what I am looking for. It’s a good start. Furniture is basically frames and boxes.

It looks like it creates one box and then mirror it across 2 different mirror planes? Nice and tidy.

I will read up on what the different GH objects do.

You must be a furniture builder :wink: Pretty close, if not spot on, to the parts needed. Don’t forget to pin the tenons!

Yes, yesterday’s version footstool_2025Jan17b.gh and today’s version footstool_2025Jan18a.gh do that, while version footstool_2025Jan17a.gh uses Move instead of Mirror.

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So, in trying to stay somewhat on track…

From what I’ve seen so far, the GH model has to be “baked” in order to get the Rhino objects drawn. Please correct me if that isn’t so…

I played with Fusion 360 for a while before buying Rhino 7. F360 seems more integrated as far as data input (lengths, widths, sketch planes, etc.), would you know? I am fine with Rhino, and don’t plan on shelving it!

At any rate, this is a good start for me.

You are correct. There are ways to turn your GH script into a command (that works without having to launch GH). If you have sliders and such you’d probably just want to leave it as a script though.

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Carl: if your foot stool workflow requires lots of dimensions and details to manufacture and especially if this is a one-shot design, stick with F360. Rhino and Grasshopper are better viewed as design exploration tools. Look at Grasshopper’s common input - the numeric slider versus F360’s text-based parameters. Grasshopper wants you to play with the object, F360 wants you to prep for manufacture.

For instance, if you wanted to play with the number and size of vertical slats in your foot stool, to find the most aesthetically pleasing - Grasshopper’s visualizations are much more fluid and fun than F360. However, doing this design in Grasshopper will take significantly more time and experience with the tool than roughing this out into F360.

Grasshopper shouldn’t be seen as an alternative to F360. They are different tools. Grasshopper is an algorithmic parametric builder - closer to code - than the drag-and-drop tool that F360 provides.

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It’s just a hobby thing.

I want to actually use it for musical instrument models, and be able to draw things like a guitar neck with , say, 24.75" scale, mandolin with 13" scale, or electric bass with 34" scale, and to have a GH file that is parameter driven in a way that can create any of those. Fret placement is a function of scale length, and does nicely in a loop. I did write a Pascal script to do a 2D sketch of a fingerboard, which can then be turned into a 3D model, but that’s not as trivial as 2D sketch.

Musical instruments can have an almost infinite number of scale lengths, and being able to get a model of a 24.625 scale vs. 25.4 scale, etc., would alleviate changing all the geometry required for other parts of the neck (nut width, fingerboard).

These old threads (2017) might be worth a look: