Thank you for your prompt response. I am using the Slic3r Perl version.

Here is the output of the commands you requested:

C:\Users\David\Documents\3D_Printer\Slic3r>perl -V
Summary of my perl5 (revision 5 version 24 subversion 1) configuration
+:

  Platform:
    osname=MSWin32, osvers=10.0, archname=MSWin32-x64-multi-thread
    uname='Win32 strawberry-perl 5.24.1.4 #1 Sun Mar 26 22:24:56 2017 
+x64'
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
<readmore>
  Compiler:
    cc='gcc', ccflags =' -s -O2 -DWIN32 -DWIN64 -DCONSERVATIVE  -DPERL
+_TEXTMODE_SCRIPTS -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -fwrapv
+ -fno-strict-aliasing -mms-bitfields',
    optimize='-s -O2',
    cppflags='-DWIN32'
    ccversion='', gccversion='6.3.0', gccosandvers=''
    intsize=4, longsize=4, ptrsize=8, doublesize=8, byteorder=12345678
+, doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=1
+6, longdblkind=3
    ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='lo
+ng long', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='g++', ldflags ='-s -L"C:\STRAWB~1\perl\lib\CORE" -L"C:\STRAWB~
+1\c\lib"'
    libpth=C:\STRAWB~1\c\lib C:\STRAWB~1\c\x86_64-w64-mingw32\lib C:\S
+TRAWB~1\c\lib\gcc\x86_64-w64-mingw32\6.3.0
    libs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 
+-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -l
+mpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    perllibs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdl
+g32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_3
+2 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    libc=, so=dll, useshrplib=true, libperl=libperl524.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=xs.dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-mdll -s -L"C:\STRAWB~1\perl\lib\CORE" 
+-L"C:\STRAWB~1\c\lib"'


Characteristics of this binary (from libperl):
  Compile-time options: HAS_TIMES HAVE_INTERP_INTERN MULTIPLICITY
                        PERLIO_LAYERS PERL_COPY_ON_WRITE
                        PERL_DONT_CREATE_GVSV
                        PERL_HASH_FUNC_ONE_AT_A_TIME_HARD
                        PERL_IMPLICIT_CONTEXT PERL_IMPLICIT_SYS
                        PERL_MALLOC_WRAP PERL_PRESERVE_IVUV USE_64_BIT
+_INT
                        USE_ITHREADS USE_LARGE_FILES USE_LOCALE
                        USE_LOCALE_COLLATE USE_LOCALE_CTYPE
                        USE_LOCALE_NUMERIC USE_LOCALE_TIME USE_PERLIO
                        USE_PERL_ATOF
  Built under MSWin32
  Compiled at Mar 26 2017 22:29:51
  @INC:
    C:/Strawberry/perl/site/lib
    C:/Strawberry/perl/vendor/lib
    C:/Strawberry/perl/lib
    .

C:\Users\David\Documents\3D_Printer\Slic3r>perl -MApp::cpanminus -le "
+print 'ok'"
Can't locate App/cpanminus.pm in @INC (you may need to install the App
+::cpanminus module) (@INC contains: C:/Strawberry/perl/site/lib C:/St
+rawberry/perl/vendor/lib C:/Strawberry/perl/lib .).
BEGIN failed--compilation aborted.

C:\Users\David\Documents\3D_Printer\Slic3r>perl -le "print for grep { 
+/(berry|perl)/ } split /;/, $ENV{PATH}"
C:\Strawberry\c\bin
C:\Strawberry\perl\site\bin
C:\Strawberry\perl\bin

C:\Users\David\Documents\3D_Printer\Slic3r>cpanm --version
'cpanm' is not recognized as an internal or external command,
operable program or batch file.

C:\Users\David\Documents\3D_Printer\Slic3r></readmore>
[download]

Weird. I just did a fresh install of Slic3r's 5.24.1 (64bit). It didn't have cpanm. However, I ran cpan, and within the cpan shell, ran install App::cpanminus, which was successful

Read more... (3 kB)

After doing that, I can successfully find and run cpanm:

Read more... (1066 Bytes)

I wonder if something got corrupted in your version of Slic3r's 64-bit Strawberry Perl. You might want to try to uninstall and reinstall, then try to install the cpanm from inside the cpan client (it shouldn't make a difference... but since the steps worked for me, maybe they will for you as well).

If that doesn't work: do you need 64bit? If not, you might follow Slic3r's instructions for the standard 32-bit Strawberry, which does come with cpanm already installed. Given that Slic3r frequently mentions 5.24, and because Strawberry 5.26 changed away from dmake to gmake (which has caused some module installation problems for some people), I'd pick the "Strawberry Perl 5.24.2.1 (32bit)" installer link from Strawberry's main page.)

update: I should point out that for this test, I was on Windows 7, not Windows 10. It might cause different behavior.

update 2: If you still have difficulty, you might be able to ask on the Slic3r issues page for them to bundle cpanm with their custom 5.24.1 64bit -- actually, you might want to ask them to do that anyway, given the difficulties you've already had.

Thank you for all your help; this issue has been resolved! I'm glad that you pointed out that I might not need the 64-bit version. I downloaded the Strawberry 5.24 32-bit version, and successfully installed. Good news, cpanminus was included.

Thanks also for testing Slic3r perl yourself. As per your suggestion, I uninstalled, redownloaded, and reinstalled Slicer perl, but I was unable to install cpanminus even from inside cpan.

Read more... (10 kB)