Many forums support Sketchfab embeds. Some forums accept them natively, which means you will find a Sketchfab button in your post editor, and you just need to copy and paste the model URL of your model to embed it. See Embed on Web Platforms.
oEmbed Support
Sketchfab models support oEmbed. This means forums that use services like Embedly or Onebox can be configured to handle Sketchfab embeds.
HTML iframe
Some forums support our iframes, so you can copy and paste the HTML embed code into the forum post.
BBCode
Some forums support BBCode embeds. It will display the thumbnail of your model with a link to view it in 3D. You can switch between HTML (iframe) and BBCode in a model's embed options.
Developer Plugins
If you want to add Sketchfab support to your forum, check out our plugins (and the oEmbed endpoint):