When Liz Mixdorf's son Meyer was confined to his hospital room following a stem cell treatment for the brain cancer he was battling, she came up with an ingenious idea to brighten his spirits.
Even she, however, could never have imagined how much joy it would bring both Meyer, five, and medical staff.
The little boy, from Arkansas, was receiving treatment at the Children's Mercy Kansas City hospital when Liz brought him in a packet of brightly coloured Post-It notes, using them to make a smiley face on his window.
"We were simply trying to entertain Meyer and keep his spirits up," she told GMA.
It wasn't long until medical staff working at the Truman Medical Centers in the building across the road from Meyer's room responded by making their own smiley face in reply.
Then began a daily game with what the boy called his 'mystery friends'.
As Johnna Schindlbeck, who works at TMC, told GMA, her smiley face was a simple way to communicate someone had seen the work. However, the boy's increasingly elaborate designs tested her creative powers.
"I thought it was cute and grabbed some notes and put up a little winky face," she said. "I thought, 'Oh wow, this escalated fast'," Schindlbeck said, adding she initially hadn't realised it was the work of a patient.
"If this little art makes him happy, gives him something to look forward to, and it makes his mother and his family know that other people care ... it was so rewarding for me to see," she continued. "I was just at the right place at the right time to be part of something that was so simply beautiful."
Occasionally, she and Meyer would catch the other putting up the designs and wave hello to one another. Eventually, Meyer was deemed fit enough to walk across the road and meet his mystery friends, including Schindlbeck.
A Facebook post from TMC shared the moment the two parties were able to meet, posting photos of Meyer playing with new gifts from staff and posing with the team who helped recreate his designs.
In an interview with local network KMBC9, who captured the moment, Mixdorf said it brought some much needed joy to each day of his six week stay.
"Every morning he would hop out of bed, as soon as someone was switching, he knew," she said.
In a recent Facebook update, Mixdorf also shared the happy news that scans had shown Meyer's brain and spine were now 'cancer free' and the pair could soon return home to Arkansas.
"Last night at 8:30pm the oncologist called us and informed us that the MRI results were in, and Meyer's brain and spine are currently CANCER FREE," she wrote.
"Meyer literally jumped in the air and exclaimed 'YES!' when we told him about the scans and that we will be heading HOME this weekend. Many happy tears of praise."