The use of shiny, flat metal instruments should be avoided to prevent the reflection from the instrument becoming a focused beam.
(The use of shiny, flat metal instruments; should be avoided; to prevent the reflection from the instrument becoming a focused beam) (the reflection from the instrument; becoming; a focused beam)
The use of shiny, flat metal instruments the reflection from the instrument
should be avoided becoming
to prevent the reflection from the instrument becoming a focused beam
a focused beam