A very easy and handy substitute for a capo are pencils and rubber bands. To prepare a capo with rubber bands and pencil is very easy.
In respect to this, are capos necessary?
A capo can be useful, but never necessary. A good guitar player must be able to change keys without a capo. Would the player feel open chords are better suited than bar chords, then a capo is an option. An option, never a necessity.
Additionally, how do you make a homemade capo for guitar?