I just updated the Custom Container Pack sources to support Delphi 10 Seattle. It was mostly a matter of creating the packages for the “new” version. I also added Delphi 10 Seattle to the compilerversion.inc file.
It now compiles and installs. I have not tested it extensively.
Custom Containers Pack (CCPack) is an integrated tool and component mini-library to produce and maintain composite controls (or simply “composites”) and other containers (forms, data modules and frames). The process of building composite components looks like ActiveForm and Frame creating, but the result is the native VCL component. You can create new composites just as usual forms.
Here is the original documentation in RTF format.