Some sketches reflect the pain and isolation of prison life, others show inmates lying on the floor, reading or cooking.
Together, the dozens of pictures drawn by ex-convict Yassin Mohamed give a rare glimpse of life in Egypt's jails.
Mohamed was first detained in 2013 aged 18 and spent five years in and out of different prisons after many arrests linked to his involvement in anti-government protests.
>> Read more: Egypt locking up transgender women in men's prisons
He took up drawing as a way to cope with the experience and to pass the time so as to avoid being drawn into criminal or radical circles in jail.
"I thought about ways I could retaliate differently," he said in an interview at his home in Cairo. "It also gives me serenity and keeps me distracted from those who hurt me."
Many of the pictures show people in crowded cells, their possessions hanging in bags. One shows a prisoner sitting in the bathroom behind a shower curtain with his head in his hands.
- Egyptian Voters Approve Referendum Extending Sissi's Rule Until 2030
- Sissi Wants West to Pay for Egyptian Brainpower. But Its Writers Cannot Return Home
- In Sissi’s Egypt, Art Has a Way of Landing You in Jail
"Many times you are unable to show your feelings in public, so you go do it in the bathroom. You can cry, or do anything else as long as you are quiet."
Another picture shows a prisoner reading the Muslim holy book the Koran in a ray of sunlight.
"Every day he would sit in a specific place to read Koran. There had to be light in the place he sat."
Prisoners cook food delivered by visiting relatives or brought from the prison canteen, and cooking at all hours of the day left a lingering smell of onions.
"All the time, every day you smell onions, onions, onions. Everyone eats onions," said Mohamed.
Thus one picture shows inmates with onions in place of their heads.
Local and international human rights groups say tens of thousands have been arrested. President Abdel Fatah al-Sisi has denied Egypt has any political prisoners.
The Tora prison in Cairo and the prison in the northern city of Tanta were the worst, Mohamed said.
"I was sitting in an empty cell that had nothing at all, wearing my prison clothes for two months, not changing my clothes or showering or doing anything at all," he said of Tanta. "The cell is truly empty, it has nothing at all."