Cannot install ruby gem in OSX

Developers Ruby API
25

After some good reading of rubygems excellent documentation I got it work on the system Ruby. These are the steps assuming that the gem is downloaded in the Download folder

First download the gem from https://rubygems.org/downloads/ruby_clipper-5.0.3.gem

Unpack the gem

gem unpack ruby_clipper-5.0.3
cd ruby_clipper-5.03

Modify lib/clipper/version.rb adding the top level namespace

module Clipper
......

to

module RG::Clipper #RG is my top level namespace

Now modify the rbclipper.cpp from

VALUE mod   = rb_define_module("Clipper");
VALUE k = rb_define_class_under(mod, "Clipper", rb_cObject);
  rb_define_singleton_method(k, "new",
                         (ruby_method) rbclipper_new, 0);

to

 VALUE top   = rb_define_module("RG"); #Top level namespace
 VALUE mod = rb_define_module_under(top, "Clipper"); #Clipper module under RG namespace
 VALUE k = rb_define_class_under(mod, "Clipper", rb_cObject);
 rb_define_singleton_method(k, "new",
                         (ruby_method) rbclipper_new, 0);

Now clipper is under the top level namespace RG.

We need to create the gemspec file. Move back to Download and extract the gemspec file from the original gem (this has not changed). This command extracts the gemspec file in ruby format (–ruby)

gem spec ruby_clipper-5.0.3.gem --ruby > ruby_clipper-5.0.3/ruby_clipper-5.0.3.gemspec

Now we need to rebuild the gem. Move back to the gem folder

cd ruby_clipper-5.0.3

and build the gem using the gemspec file just created

gem build ruby_clipper-5.0.3.gemspec

At this point we can install the modified gem from the local file (we are still in the gem folder)

sudo gem install --force --local ruby_clipper-5.0.3.gem

--force #Ignore dependencies
--local #Restrict operations to the LOCAL domain

The (modified) gem is now installed in system Ruby.

In irb we can write

require 'clipper'
c = RG::Clipper::Clipper.new

and get

=> #<RG::Clipper::Clipper:0x007f8ea232ca48 @multiplier=1048576>

Now I move

/Library/Ruby/Gems/2.0.0/gems/ruby_clipper-5.0.3/ext/clipper/clipper.bundle

to my SU RG folder

Users/ruggiero/Library/Application Support/SketchUp 2015/SketchUp/Plugins/RG/ext

but when i require clipper

require 'RG/ext/clipper'

I get a ugly bug splat!!!

Am i doing something wrong?

Thanks