Building a pen plotter

I’ve got it into my head that I want to build a pen plotter. I think they are very cool and I’m conscious that I’d like to have some more physical hobbies. Things I’m hoping to get out of this project:

• A physical project I can explore generative art with
• Some bonding time with my eldest
• More confidence in bringing physical ideas into being
• Fuel for ideas both physical and digital

I spent some time reading through Instructables and read through a lot of the material on Drawing Bots website. I joined that Discord and asked some questions.

I couldn’t decide initially whether I should buy a kit or try to build this myself. Encouraged by the Discord, I decided to follow the adventue and build myself. Most of the tutorials and guides I’ve found suggested using an Ardunio Uno and a motor shield - I’ve done some work with Ardunio before and this seemed sensible but a Discord member had a different idea:

In retrospect, this seems so obvious I feel silly for not thinking about this myself but this is a learning journey so here I go. I have a list of parts also known as “Bill of Materials” or BOM and here’s what it looks like right now:

Item	Qty	Unit Price	Est Total	Purchase link	Actual cost
SKR Mini E3 V3.0 board	1	£45	£45	Board from Amazon	£48.89
NEMA 17 stepper motors	2	£12	£24	Motor from PiHut	£24 (+P&P)
SG90 Micro Servo	1	£9	£9	Already have this	£0
12 V ATX PSU (reused/spare)	1	£0–20	~£10
V-slot, rods, pulleys, belts	—	—	£30	Separate table ⬇️	£38.97
3D-print filament + misc parts	—	—	£15	Got these	£0
Total	—		£130–140		£111.86

I don’t know how realistic those numbers are and I don’t know how to make this thing but I’m keen to give it a go. Alongside those, I’ll need to use my 3D printer to get some of the parts like the pen holder and then I’ll need to work out how to code it all. I’m less nervous about those parts as I understand them better.

There’s a line on there that looks ambigious and impenetrable - the one about pulleys and rods and things - I don’t know where to start there.

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So, I think this is what I need but could be well off:

Item	Price	Link
V Slot extrusion	£17.99	Amazon
Timing belt and pulley kit	£12.99	Amazon
Wheels	£7.99	Amazon
Total	£38.97

In my head, I think I can 3D print the rest of the necessary components but I’ll need to think a bit harder and get some advice.

I’m going to explore a few more sites for costs and designs - Discord already been helping me out with links.

They also linked me to their own notes which are an absolute treasure trove of information.

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Gathering prior art

To help nail down the design I want to build, I’m collecting together some prior art with links to the builds:

I think that my main options for design are:

• a C shape (like the illustration at the top of this post)
• a T shape which seems to be the most popular
• a H shape which encloses the draw space more clearly

The things that are consistent across builds are the need for a board and motors. I’ll go ahead and get those while I think about design. As I think about it, I think the “C” is just an unenclosed “H”, so maybe there are only two options.