And to make it read-able reverse those steps at the other end ! 😞
The only way to give someone else your actual skp file in a way that won't be very 'useful' to them is to copy it and explode every group and instance [then purge], remove layers, styles etc and sabotage bits and bobs so it is not at all user friendly.
They can still edit it but it won't be very useful for 'harvesting' or reuse...
Alternatively make a 3D PDF of it so they can still look around it and print off, but not edit it.
You can make it read-only but that can be undone in a second.
You can ship it with a special ruby that limits what can be done to it - but simply removing the ruby from the plugins folder will scupper that plan...
No one has come up with a way of 'locking' or 'password protecting' skp files - enough have tried... 😡