Bonsai BIM: the free BIM tool, and how AI pulls counts and quantities from it
Bonsai gives you free tools for working with building models. An AI Employee could help your team get useful sheets out of them, with a setup built for your company.
6 minute read
An AI Employee can be set up to work with Bonsai to read IFC models, pull quantities and check for missing data before preparing sheets for your team to review. VeebarTech has not built this connection for clients yet, so the work would start with your files and a test of the tasks you need.
- Bonsai is free and open source, and runs inside Blender.
- It suits firms that want open building models and can handle some learning.
- An AI Employee can handle repeat model tasks once the connection is built and tested.
- Your team still checks the results and makes the job decisions.
What does Bonsai actually do?
Bonsai turns Blender, a free program for making models, into a building information modelling tool. That is what BIM stands for. A BIM model can hold facts about a door or wall along with its shape, so it can help answer questions about the job.
You can build, check and share building models in IFC, an open file format. Think of it as a way to pass building information between tools. What comes through still depends on what the person who made the model put into it.
Bonsai is free and open source, and its website says it is free forever. Blender is free too. You still need time to learn the tools and check the work, so free software does not mean a job takes no effort.
A model earns its keep when your team can get useful work out of it.
Would a small construction firm use it?
Bonsai can suit a small design and build firm that wants proper IFC models without paying for Revit seats. You might need quantities for a quote or a model to help sort out where building parts meet. Those are real needs, even in a small office.
The catch is the learning curve. Someone needs to understand how the model is put together and what the fields mean. If your estimator already spends the afternoon chasing a sub for a quote, asking them to learn another tool needs a clear payoff.
Start with the work you need to hand over. A door schedule is a list of doors and their details. If that is what the site needs, judge Bonsai by how well it helps you produce that sheet from the files you receive.
How popular is Bonsai?
Blender Extensions reports more than 166,000 Bonsai downloads as of November 2026. The same Blender Extensions listing shows a 5.0 out of 5 rating from 58 reviews. That shows interest and good feedback from those reviewers, though downloads do not tell us how many firms use it each day.
GitHub IfcOpenShell/IfcOpenShell reports about 2,900 stars and 1,000 forks as of November 2026. That repository holds Bonsai as well as the wider IfcOpenShell project. Those counts show interest in the code, rather than a count of Bonsai customers.
The Bonsai website says hundreds of contributors keep the project going. If you know the old name, BlenderNation reports that the release which renamed BlenderBIM to Bonsai shipped in September 2024. Older guides may use that earlier name.
Your team keeps the tools it knows. The AI Employee takes the busywork around them.
What do people find slow or frustrating?
Getting started can be hard. In the supplied OSArch forum reports, new users said they struggled to find help on how to build a model. That matters when you need a useful sheet for tomorrow and cannot spend the afternoon working out where to click.
Other reports describe slow startup and crashes during clash checks on large models. A clash check looks for building parts that run into each other. These are user reports about particular setups, so they should not be read as proof that every job will hit the same trouble.
There are also reports of Bonsai builds failing with some Blender versions. Before you depend on it for a deadline, test the versions you plan to use with a copy of your own model. Keep a working setup while you check any update.
- Learning the tool can eat into the time you hoped to save on a takeoff.
- Slow startup adds friction when you only need to check a small detail.
- A failed clash check means someone still has to find another way to finish the review.
- Version problems can stop the work before you even get the model open.
Free software still needs a working setup and someone who knows what a good result looks like.
How could an AI Employee help with Bonsai?
When we say AI in Bonsai, we mean an AI Employee set up to work with Bonsai. Bonsai is built on IfcOpenShell, which provides code tools for reading and working with IFC files. That gives us a route to build repeat tasks around your models.
BonsaiWith that setup, an AI Employee can pull quantities or prepare door and room schedules. It can flag missing model data and export clean sheets for review. Your estimator can then spend time checking the scope and calling suppliers instead of retyping model details into a spreadsheet.
We have not built this connection for clients yet, and we are not an official Bonsai partner. We would need to test your files and agree on the checks before you rely on the output. To explore another task in the meantime, Try a free construction tool.
| Task | Doing it by hand in Bonsai | Bonsai plus an AI Employee after setup |
|---|---|---|
| Pull quantities | Choose the model items and prepare the quantity sheet. | Run agreed quantity rules and prepare a sheet for review. |
| Prepare a door schedule | Gather door details and arrange the columns. | Pull the agreed fields into your sheet format. |
| Check missing data | Inspect the fields needed for the job. | Flag blank required fields for someone to resolve. |
| Export a clean sheet | Repeat the export and tidy the result. | Prepare a consistent export using the agreed format. |
How would we set it up for your company?
We would start with a task that already lands on someone's desk. Maybe your office manager copies room details into a handover sheet whenever a revised model arrives. Bring that sheet and a sample model, so the test has a clear target.
The setup needs rules from your team. Which rooms belong in the sheet, and what should happen when a room has no name? An AI Employee should flag that gap for review rather than fill it with a guess.
The first test should use a copy of the model. We would compare the output with a result your team has checked. That gives you something concrete to judge before the task becomes part of the job routine.
- Choose a repeat task with a clear output, such as a room schedule.
- Share a sample IFC model and the sheet your team wants to receive.
- Agree on the fields and units, plus which missing details must be flagged.
- Build the connection through the model tools or exports that suit the task.
- Compare the result with a checked sample and fix any rules that give the wrong output.
- Name the person who reviews the sheet before it goes to the site or into a quote.
Is this worth trying on your next job?
If all you need is open BIM work, Bonsai is worth a look before you pay for seats you may not need. The real question is how much effort it takes to get a checked result. A free tool can still demand a lot of staff time.
An AI Employee makes sense when the same model task keeps coming back. It cannot walk your site or decide that an unclear drawing is safe to build from. Your people keep those calls, with less copying and checking of routine fields on their desks.
We would look at your current task before suggesting a build. If you want to see what might fit, See the AI Employee for design teams. Bring a sample of the sheet you need and explain what slows your team down.
Use Bonsai by hand
Choose this when Model work is occasional and someone knows the tool.
Keep the process simple. Save the steps that work so the next model does not mean starting from scratch.
Explore an AI Employee
Choose this when The same sheets or data checks come back on each job.
Test a repeat task using your files. Look at the time spent correcting the output as well as preparing it.
Sort out the model first
Choose this when Key details are missing or nobody owns the review.
Agree on what the model must contain and who checks it. Then test how much repeat work can be handled for you.
Questions owners ask
Is Bonsai free for business use?
Bonsai is free and open source, and its website says it is free forever. It runs on Blender, which is also free. Your business still needs to allow for learning and checking the work. A custom AI Employee connection would be separate work with a scope to agree on.
Does Bonsai replace Revit for every job?
We would not make that promise. Bonsai can suit work built around open IFC models, but you need to check what your client and project team expect you to deliver. Test a real file and the required output before changing a process that your current jobs depend on.
Can an AI Employee read our IFC files?
An AI Employee can be set up to read IFC files through tools such as IfcOpenShell. The useful result depends on what the file contains and the rules you set. We would test your models before promising a particular schedule or quantity sheet, and flag missing data for review.
Will our estimator still need to check quantities?
Yes. Your estimator still needs to check that the quantities match the scope and the model used for the quote. An AI Employee can reduce repeat copying and prepare a review sheet. It cannot know that an item left out of the model was meant to be included.
Can we use this Bonsai connection today?
We have not built this connection for clients yet. We would start by reviewing your task and sample files, then build and test a setup for your company. We are not an official Bonsai partner. The aim is to give your current team more time for the work they were hired for.