Put this file in the busybox source folder and run, then it will make all variants of busybox for ARM and MIPS architecture. (A few variants cannot be built)

make-mips-arm-busybox.sh

build()
{
    if [ ! -f $1-$i ] ; then
        echo Building $1-$i...
        make clean > /dev/null
        time make CROSS_COMPILE="$CROSS_COMPILE" CFLAGS+="$_CFLAGS" CXXFLAGS+="$_CXXFLAGS"
        mv $1 $1-$i
    else
        echo Skipping $1-$i since the output file already exists
    fi
}

if [ "$#" -gt 0 ]; then
    CROSS_COMPILE=arm-linux-gnueabi-
    for i in armv4t armv5t armv5te armv6 armv6j armv6k armv6kz armv6t2 armv6z armv6zk armv7 armv7-a armv7ve armv8-a armv8.1-a armv8.2-a armv8.3-a armv8.4-a armv8.5-a armv7-r armv8-r armv6-m armv6s-m armv7-m armv7e-m armv8-m.base armv8-m.main; do
        _CFLAGS=" -march=$i -static"
        _CXXFLAGS=" -march=$i -static"
        build $1
    done
    
    CROSS_COMPILE=mips-linux-gnu-
    for i in mips1 mips2 mips3 mips4 mips32 mips32r2 mips64 mips64r2; do
        _CFLAGS=" -march=$i -static"
        _CXXFLAGS=" -march=$i -static"
        [ "$i" = "mips1" ] && _CFLAGS+=" -mfp32"
        build $1
    done
else
    echo Usage $0 [output-prefix]
    echo Example: $0 busybox
    echo Result: the output file will be busybox-armv4t, busybox-armv5t...
fi