I redesigned the connection to L. Friends as below, closer to L. spec, and added an extra bit of bed adhesion for a previously floating area. It's still not the exact L. oval but this slot fits much better than the original, I printed tested multiple copies.

3 fits available:

Recommended L.-style fit:

• Snug (if printing at 0.08/0.1 layer height, and are confident you aren't over-extruding) this is resistance to remove so a child can play with it, but it is not hard to remove.

Optional:

• Slip (snug fit that slides on, but slides off in the hand)
• Loose (if you are printing higher layer heights or find you are over-extruding)