This is a simple setup to allow your designer ftp access to a web directory. The problem that I encountered was for a web server running wordpress. Apache runs as the user www-data with an id of 33 on Ubuntu 12.04. The wordpress files have to be ownership as the webserver for you to download and install updates through wordpress’s web interface. I guess I could just have the core wordpress files and the plugins directory and given the rest the user account permissions but I didn’t. The Pure-ftp server allow me to create virtual users and I can give them any uid, except 0 (root). For security, I would just allow from the designers ip address.
apt-get install pure-ftpd
echo "41000 42000" > PassivePortRange echo "yes" > DontResolve echo "33" > MinUID
pure-pw useradd someuser -u www-data -d /var/www pure-pw mkdb
cd /etc/pure-ftpd/auth ln -s ../conf/PureDB 50pure
iptables -A INPUT -s $ip -p udp --dport 21 -j ACCEPT iptables -A INPUT -s $ip -p tcp --dport 21 -j ACCEPT iptables -A INPUT -s $ip -p udp --dport 41000:42000 -j ACCEPT iptables -A INPUT -s $ip -p tcp --dport 41000:42000 -j ACCEPT