make a new maya shelf (solo projects only). uses a template file in $MY_PROJECT/aux if it exists

mkshelf.bash

#!/bin/bash

if [ -z "$1" ]; then
  printf "%bPlease pass a name for the new shelf (e.g. model_tools)%b\n" "${FG_RED}" "${NORMAL}"
  exit 1
fi
name=$1

generate_shelf_empty() {
cat << EOF > ${new_shelf}
global proc shelf_${1} () {
    global string \$gBuffStr;
    global string \$gBuffStr0;
    global string \$gBuffStr1;
}
EOF
}

MY_MAYA_SHELVES_DIR="${MY_PROJECT}/custom/maya/shelves"

template_shelf="${MY_PROJECT}/aux/maya/shelf_Template.mel.py"
new_shelf="${MY_MAYA_SHELVES_DIR}/shelf_${name}.mel"

# Prefer a template shelf in $MY_PROJECT/aux, generate new if it does not exist
if [ ! -f "${new_shelf}" ]; then
  if [ -f "${template_shelf}" ]; then
    cp ${template_shelf} ${new_shelf} && \
    pyp "lose('//') | p.format(Name=\"$name\")" < "${template_shelf}" > ${new_shelf}
  else
    generate_shelf_empty $name
  fi
else
  printf "%berror: A shelf named %s already exists, exiting...%b\n" "${FG_RED}" "$name" "${NORMAL}"
  exit
fi

shelf_Template.mel.py

// -*- mode: MEL -*-
global proc shelf_{Name} () {{
    global string $gBuffStr;
    global string $gBuffStr0;
    global string $gBuffStr1;

    shelfButton
        -enableCommandRepeat 1
        -enable 0
        -width 35
        -height 35
        -manage 1
        -visible 1
        -preventOverride 0
        -annotation "spacer"
        -enableBackground 0
        -align "center"
        -label "Spacer"
        -labelOffset 0
        -font "plainLabelFont"
        -overlayLabelColor 0.8 0.8 0.8
        -overlayLabelBackColor 0 0 0 0.25
        -image "vacantCell.png"
        -image1 "vacantCell.png"
        -style "iconOnly"
        -marginWidth 1
        -marginHeight 1
        -sourceType "mel"
        -commandRepeatable 1
    ;
    shelfButton
        -enableCommandRepeat 1
        -enable 1
        -width 35
        -height 35
        -manage 1
        -visible 1
        -preventOverride 0
        -annotation "Create a new button on the {Name} Shelf"
        -enableBackground 0
        -align "center"
        -label "CreateNewButton"
        -labelOffset 0
        -font "plainLabelFont"
        -imageOverlayLabel "btn+"
        -overlayLabelColor 0.8 0.8 0.8
        -overlayLabelBackColor 0 0 0 0.8
        -image "defaultSingleLayout.png"
        -image1 "defaultSingleLayout.png"
        -style "iconOnly"
        -marginWidth 1
        -marginHeight 1
        -command "import pymel.core as pm\n\nbtn = pm.shelfButton(\n\tlabel=\"NewButton\",\n\tparent=\"{Name}\",  # SET ME TO THE CURRENT SHELF NAME \n\timage=\"defaultSingleLayout.png\", \n    sourceType=\"python\",\n    command=\"import pymel.core as pm\",\n\tannotation=\"\",\n\toverlayLabelBackColor=[0, 0, 0, 0.8],\n    imageOverlayLabel=\"#####\")"
        -sourceType "python"
        -commandRepeatable 1
    ;
    shelfButton
        -enableCommandRepeat 1
        -enable 1
        -width 35
        -height 35
        -manage 1
        -visible 1
        -preventOverride 0
        -annotation "Create a new spacer on the {Name} Shelf"
        -enableBackground 0
        -align "center"
        -label "CreateNewSpacer"
        -labelOffset 0
        -font "plainLabelFont"
        -imageOverlayLabel "spcr+"
        -overlayLabelColor 0.8 0.8 0.8
        -overlayLabelBackColor 0 0 0 0.8
        -image "defaultSingleLayout.png"
        -image1 "defaultSingleLayout.png"
        -style "iconOnly"
        -marginWidth 1
        -marginHeight 1
        -command "import pymel.core as pm\n\nbtn = pm.shelfButton(\n\tlabel=\"Spacer\",\n\tparent=\"{Name}\",\n\timage=\"vacantCell.png\",\n\tenable=False,\n\tannotation=\"spacer\")"
        -sourceType "python"
        -commandRepeatable 1
    ;
}}