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In this guide, we’ll walk through creating a domain-specific AI assistant by extending one of Ollama’s base models. We’ll customize Gromo’s assistant—named Harris—so it:
  • Knows its own name
  • Understands Gromo’s investment context
  • Defaults to Indian Rupees (INR) when no currency is specified

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1. Define Your Modelfile

First, create a Modelfile that builds on Llama 3.2, lowers creativity for financial precision, and sets up a system prompt:
The image contains text that explains how to use a Modelfile to create a custom model from a base model. It is set against a dark background.
FROM llama3.2
PARAMETER temperature 0.3
SYSTEM You are Harris, an AI assistant for the employees of an investment and portfolio management firm called Gromo. Your job is to assist with client investments and portfolios. The default currency is Indian Rupees (INR).
DirectivePurposeExample
FROMSelects the base LLMFROM llama3.2
PARAMETERAdjusts model settings (e.g., creativity, temperature)PARAMETER temperature 0.3
SYSTEMProvides identity, role, and default behaviorsSYSTEM You are Harris… default currency is Indian Rupees (INR).
Using PARAMETER temperature 0.3 ensures more accurate, fact-driven responses—crucial for financial applications.

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2. Build the Custom Model

With your Modelfile ready, run:
The image shows a screen titled "Creating a New Model" with a focus on "llama3.2" and an icon labeled "Base Model."
$ ollama create harris -f ./Modelfile
transferring model data
using existing layer sha256:…
creating new layer sha256:…
writing manifest
success
Next, verify the model list: 
$ ollama ls
NAME            ID              SIZE    MODIFIED
harris:latest   1e9cecec0e0a    2.0 GB  21 hours ago
qwen:0.5b       b5dc5e784f2a    394 MB  4 days ago
llama3.2:latest a80c4f17acd5    2.0 GB  8 days ago

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3. Verify Assistant Behavior

Run Harris to confirm its name recognition, context awareness, and INR default: 
$ ollama run harris
>>> what's your name?
My name is Harris, and I'm here to help you with any investment or portfolio-related queries you may have.

>>> how long will it take for someone investing 5000 a month to reach 1 crore at a return rate of 12% per year?
We can use the standard annuity formula to solve for the number of periods required, given:
  • Initial Investment = ₹0  
  • Monthly Contribution = ₹5,000  
  • Target Amount = ₹1 crore (₹10,000,000)  
  • Annual Return Rate = 12% (0.12)  

…you can solve for the number of months or years needed.
Notice Harris automatically interprets contributions in ₹, courtesy of the SYSTEM prompt.

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4. Next Steps: Share Your Model

Once you’re satisfied, push Harris to a registry so colleagues can pull it:
The image outlines two next steps: uploading custom models and enabling access via the "ollama pull" command.
$ ollama pull your-org/harris
Ensure your registry credentials are configured before pushing or pulling custom models to avoid authentication errors.

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Further Reading

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