Sound Game lesson plans (Montessori album pages) outline how to explore sounds with children aurally (by ear), with and without objects. The ability to identify sounds in various placements of words before even considering alphabets, reading or writing, lay a strong foundation for any reading/writing program to come.

The sound games can begin at age 2, but are useful even for adults to fine-tune their listening skills! Typically, they are used in a Montessori environment with the 2.5 to 4 year olds.

These lesson plans provide a step by step format through all the sounds in our English language. These sounds are entirely independent of the spelling of any word, so we don't need letter representations: no alphabet, no sandpaper letters, no visual needed except a few objects at the very beginning that can be picked up from around your home or school. Don't think you have many small objects? The last few pages of the document provide tips on what can be used, without needing to purchase a single item.

Also, see this post at Montessori Trails to see what can be very easily found around your home.
Montessori Trails: Montessori Small Objects

This document includes suggested word lists, but this is just a starting point: you can modify and adjust as you see fit for the children you work with.