that is what plexiglass if for to slow down things like that . get a pice 1/4 thk. from the local hardware store . also the pices have such low mass they don't fly too fare but if caught right they will , no that is with a standard endmill . Inserted tooling can and will make things fly faster . you can slow your feed down to 25-50 % of what your running and the slug will drop .