• ketter writers,
• petter writers,
• oetter writers,
• lwtter writers,
• lstter writers,
• ldtter writers,
• lrtter writers,
• l4tter writers,
• l3tter writers,
• lerter writers,
• lefter writers,
• legter writers,
• leyter writers,
• le6ter writers,
• le5ter writers,
• letrer writers,
• letfer writers,
• letger writers,
• letyer writers,
• let6er writers

The adjective form of the word "letter writers" is "letter-writing". For example, you could say "She is a letter-writing enthusiast".

The plural form of the word "letter writer" is "letter writers".

The singular form of the word "letter writers" is "letter writer"