#Bash, 179 bytes

echo U`sed -r 's/./& &/g'<<<HAABADEDOEFAEHELAGOFEMAHINAISHMENERESITALOHOMMONOPAMUMYAWETOSOWOYOXUNUPEXI`F `grep -o ..<<<ANARASATAXAYBEBIBOBYJOKAKILIMIOIDOIDORPIQITIUSUTYEZA`

• Saved 7 bytes thanks to Adam Katz comment

It uses sed to do regex replacement. First regex input is based on Sp3000 idea while second regex uses common input without spaces.

Explanation:

echo              print to standard output the following
U                 boundary U character
sed -r [etc]      the result of replacing regex
    .             select a character
    & &           replace it for: matched char, space, matched char
    g             do it globaly for every character
    <<<HAAB[etc]  string input based on Sp3000 idea => HA AA AB ...
F                 boundary F character
sed -r [etc]      the result of replacing regex
    ..            every two characters
    <space>&      for space+matched character
    g             do it globally
    <<<ANAR       normal input => AN AR ...

Bash, 179 bytes

echo U`sed -r 's/./& &/g'<<<HAABADEDOEFAEHELAGOFEMAHINAISHMENERESITALOHOMMONOPAMUMYAWETOSOWOYOXUNUPEXI`F `grep -o ..<<<ANARASATAXAYBEBIBOBYJOKAKILIMIOIDOIDORPIQITIUSUTYEZA`

• Saved 7 bytes thanks to Adam Katz comment

It uses sed to do regex replacement. First regex input is based on Sp3000 idea while second regex uses common input without spaces.

Explanation:

echo              print to standard output the following
U                 boundary U character
sed -r [etc]      the result of replacing regex
    .             select a character
    & &           replace it for: matched char, space, matched char
    g             do it globaly for every character
    <<<HAAB[etc]  string input based on Sp3000 idea => HA AA AB ...
F                 boundary F character
sed -r [etc]      the result of replacing regex
    ..            every two characters
    <space>&      for space+matched character
    g             do it globally
    <<<ANAR       normal input => AN AR ...

#Bash, 179 bytes

echo U`sed -r 's/./& &/g'<<<HAABADEDOEFAEHELAGOFEMAHINAISHMENERESITALOHOMMONOPAMUMYAWETOSOWOYOXUNUPEXI`F `grep -o ..<<<ANARASATAXAYBEBIBOBYJOKAKILIMIOIDOIDORPIQITIUSUTYEZA`

• Saved 7 bytes thanks to Adam Katz comment

It uses sed to do regex replacement. First regex input is based on Sp3000 idea while second regex uses common input without spaces.

Explanation:

echo              print to standard output the following
U                 boundary U character
sed -r [etc]      the result of replacing regex
    .             select a character
    & &           replace it for: matched char, space, matched char
    g             do it globaly for every character
    <<<HAAB[etc]  string input based on Sp3000 idea => HA AA AB ...
F                 boundary F character
sed -r [etc]      the result of replacing regex
    ..            every two characters
    <space>&      for space+matched character
    g             do it globally
    <<<ANAR       normal input => AN AR ...

#Bash, 179 bytes

echo U`sed -r 's/./& &/g'<<<HAABADEDOEFAEHELAGOFEMAHINAISHMENERESITALOHOMMONOPAMUMYAWETOSOWOYOXUNUPEXI`F `grep -o ..<<<ANARASATAXAYBEBIBOBYJOKAKILIMIOIDOIDORPIQITIUSUTYEZA`

• Saved 7 bytes thanks to Adam Katz comment

It uses sed to do regex replacement. First regex input is based on Sp3000 idea while second regex uses common input without spaces.

Explanation:

echo              print to standard output the following
U                 boundary U character
sed -r [etc]      the result of replacing regex
    .             select a character
    & &           replace it for: matched char, space, matched char
    g             do it globaly for every character
    <<<HAAB[etc]  string input based on Sp3000 idea => HA AA AB ...
F                 boundary F character
sed -r [etc]      the result of replacing regex
    ..            every two characters
    <space>&      for space+matched character
    g             do it globally
    <<<ANAR       normal input => AN AR ...

#Bash, 179 bytes

echo U`sed -r 's/./& &/g'<<<HAABADEDOEFAEHELAGOFEMAHINAISHMENERESITALOHOMMONOPAMUMYAWETOSOWOYOXUNUPEXI`F`sed -r 's/../ &/g'<<<ANARASATAXAYBEBIBOBYJOKAKILIMIOIDOIDORPIQITIUSUTYEZA`

It uses sed to do regex replacement. First regex input is based on Sp3000 idea while second regex uses common input without spaces.

Explanation:

echo              print to standard output the following
U                 boundary U character
sed -r [etc]      the result of replacing regex
    .             select a character
    & &           replace it for: matched char, space, matched char
    g             do it globaly for every character
    <<<HAAB[etc]  string input based on Sp3000 idea => HA AA AB ...
F                 boundary F character
sed -r [etc]      the result of replacing regex
    ..            every two characters
    <space>&      for space+matched character
    g             do it globally
    <<<ANAR       normal input => AN AR ...

#Bash, 179 bytes

echo U`sed -r 's/./& &/g'<<<HAABADEDOEFAEHELAGOFEMAHINAISHMENERESITALOHOMMONOPAMUMYAWETOSOWOYOXUNUPEXI`F `grep -o ..<<<ANARASATAXAYBEBIBOBYJOKAKILIMIOIDOIDORPIQITIUSUTYEZA`

• Saved 7 bytes thanks to Adam Katz comment

It uses sed to do regex replacement. First regex input is based on Sp3000 idea while second regex uses common input without spaces.

Explanation:

echo              print to standard output the following
U                 boundary U character
sed -r [etc]      the result of replacing regex
    .             select a character
    & &           replace it for: matched char, space, matched char
    g             do it globaly for every character
    <<<HAAB[etc]  string input based on Sp3000 idea => HA AA AB ...
F                 boundary F character
sed -r [etc]      the result of replacing regex
    ..            every two characters
    <space>&      for space+matched character
    g             do it globally
    <<<ANAR       normal input => AN AR ...