Is AI CAD worth it? A maker's cost-of-time calculation
Put a value on your evenings and the maths is short: a few dollars a month against hours of CAD, or against parts you never made. Break-even, and when it does not pay.
The two costs
Every 3D printed part costs you filament (cents) and time (the real cost). A functional part in desktop CAD takes a competent hobbyist 30 minutes to 3 hours; the same part described to an AI takes 5 to 15 minutes. The question is what your hour is worth and how many parts you make.
The calculation
Take a modest value for an evening hour, say $20, and a modest habit, four parts a month.
| Desktop CAD | AI CAD | |
|---|---|---|
| Time per part (average) | 55 min | 10 min |
| Parts per month | 4 | 4 |
| Hours per month | 3.7 h | 0.7 h |
| Time cost at $20/h | $73 | $13 |
| Software | $0 (hobby licence) | $14.99 (Pro, 200 credits: four parts spend about 20) |
| Monthly cost | $73 | $28 |
The plan pays for itself on the first part of the month. If you print fewer parts, Maker ($7.99 a month for 50 credits) covers about 10 typical parts a month: that is about $183 of CAD time against about $41 with AI, Maker included.
The hidden column: parts you never made
The bigger saving is not on the parts you would have modelled anyway. It is the drawer divider, the cable clip, the replacement foot you did not make because 40 minutes of CAD was not worth a $0.30 part. At ten minutes it is. Most people who switch print more, not the same amount faster.
Credits, explained in time
A new part spends 4 credits on a plan, whichever model answers, its first 3 small changes free (3 without a plan), a design change 3, a small change 2, a quick edit that changes a size or a number 1, and downloads are included in every plan, so a typical part with a change and a few quick edits spends about 5. Maker gives 50 a month for $7.99 (enough for about 10 parts), Pro gives 200 for $14.99 (about 40 parts a month, counting the requests that shape each one), and Unlimited has 300 AI requests a month included and unlimited downloads. Turning the model around and typing numbers in the viewer are free, and so is downloading again after a fix. So the credits follow the AI work: iterating spends them, the file itself is included, and a small fix typed in the viewer costs nothing.
When it does not pay
- You model daily in a professional CAD tool for work and already have templates for everything. Your hour of CAD is 15 minutes, and the saving is small.
- Your prints are art: sculpts, figurines, terrain. AI CAD is for engineering shapes.
- You print a few things a year. A plan running all year does not pay; take a month of Maker ($7.99, 50 credits, about 10 parts) when you have something to print, then cancel.
When it clearly pays
- You do not know CAD and were going to learn it "some weekend".
- You make enclosures, brackets, organizers, adapters and replacement parts.
- You iterate: the first print is never the last.
- You want to design at the printer, on a phone or a tablet, not at a workstation.
Break-even in one line
If describing a part saves you more than 45 minutes a month, Pro is cheaper than your time. It saves that on the first part.
Prompts to start from
Open one in the builder, change the numbers to yours, and the model renders in your browser, usually within a minute or two. Keep adjusting in the chat before you print.A cable clip for three 5 mm cables that sticks under a desk edge: a 30 x 20 mm base 2 mm thick with three C-shaped clips 0.3 mm smaller than the cables.
A replacement rubber foot for a chair leg: 25 mm outer diameter, 15 mm tall, an 18 mm bore 10 mm deep for the leg with a 0.2 mm press fit, 1 mm chamfer at the base.
Questions
A new part spends 4 credits on a plan, whichever model answers, its first 3 small changes free (3 without a plan), a design change 3 (2 for a small change, 1 for a quick edit), and downloads are included in every plan (4 credits without one); turning the model around and changing its numbers in the viewer are free. Maker is $7.99 a month for 50 credits (enough for about 10 parts), G-code sliced for your printer included like the STL. Pro is $14.99 a month for 200 credits (about 40 parts a month, counting the requests that shape each one), and Unlimited is $79.99 a month for 300 AI requests a month and unlimited downloads. Cancel a plan anytime.
The software is not free if you count your time. At even $20 an hour, four parts a month cost about $73 of CAD time versus about $28 with an AI tool including the plan.
No. Unused plan credits stay on your account until you use them, even if you cancel, and your models stay saved and editable.