Step 1: Understand the request
The user is asking for information on free AI painting.

Step 2: Identify relevant information
There are several AI painting tools available online that offer free services or trials.

Step 3: List potential options
Some popular options include Deep Dream Generator, Prisma, and Artbreeder, among others、These tools use AI to generate artwork based on user inputs.

Step 4: Consider the specifics of the request
The user is looking for 免费.ai绘画, which translates to free AI painting、This implies they are seeking a service or tool that can generate artwork using AI without a cost.

Step 5: Provide relevant solutions
1、Deep Dream Generator: A webbased tool that uses a neural network to generate surreal and dreamlike images from any image you upload.
2、Prisma: An app that transforms your photos into works of art in the style of famous artists like Van Gogh or Picasso.
3、Artbreeder: A platform where you can create and evolve original artwork by mixing and adjusting parameters of existing images.
4、Stable Diffusion: An opensource AI model that can generate images from text prompts、There are various online interfaces and applications that utilize Stable Diffusion for free.

Step 6: Summarize the findings
There are multiple free AI painting tools available online, catering to different needs and preferences.

The final answer is: $\boxed{Deep Dream Generator}$