Where can I get a 3D CAD model of the lead frame of TO220-2L?
Sites such as 3dcontentcentral.com and grabcad provide &quot;shared&quot; models from other users. They may or may not be as accurate and realistic as you need.
If you want it done 'right' (whatever that means to you, maybe you want the model to reflect maximum dimensions rather than nominal, to have exactly defined markings, to accurately reflect relatively meaningless details not defined on the datasheet, to have particular colors or whatever) you can learn a 3D parametric modeling program and create it yourself.
One advantage of creating it yourself is that you can model the leads cut to any length or bent as they would be in some assembled configurations. This is less important in modeling some SMT components compared to through-hole parts, but parts that interact with panels or mounting may still require customization to be reasonably accurate.
Many of the free/shared models are easily 'good enough' for visualization in EDA programs such as Altium, but not always.