WENATCHEE — When Marlin Peterson unleashed two 80-foot arachnids on a Seattle rooftop, the Wenatchee artist liked to ride up the Space Needle elevator just to hear his audience react. “Eww gross!” was to be expected. “Whoa, cool” was a nice surprise.

“My favorite reaction, and the one I was going for — a lot of people can’t tell if it’s a sculpture or it’s a painting,” Peterson said. “They’d argue back and forth, ‘No, it’s a sculpture, look at this part.’ That was definitely the most rewarding.”

In the hot August sun, Peterson spent several days rolling thick lines of gray paint to create the illusion of a shadow. The 3-D effect is called trompe l’oeil (sounds like tromploy), French for “trick the eye.”

He chose daddy longlegs specifically with their shadow in mind: A round, speckled abdomen with two mouth parts sticking out like fangs, suspended high above the ground from eight spindly legs.

“I think it’s also the underappreciated nature of opiliones,” Peterson said, referring to daddy longlegs’ scientific name. “These things are everywhere, in the yard, in the house, right now. People generally don’t take a moment to check them out. I like this because it gives people a chance to really stare before it runs away.”

He consulted with a daddy longlegs expert at the Burke Museum of Natural History and Culture in Seattle to make sure the drawing was scientifically accurate.

Peterson also hoped to paint a bored circus character with a sign that read, “Rides $3.50.” He finished the colossal arachnids in late August, which didn’t leave enough time for more.

The rooftop mural was a year in the making. Artist Trust granted Peterson $1,500 to paint the 3-D mural last fall, but it took three months to find a building owner willing to let him cover a wall with spiders.

“It was like a full-time job going around Seattle on my bike looking around to different walls and trying to find the perfect wall,” Peterson said.

Before the mural project, the 37-year-old worked as a freelance illustrator in the Seattle area. He moved to Wenatchee in May. Two years ago, he painted a mural of a young girl staring at a slug on a wall near Hilltop as part of the Tacoma Mural Arts program.

This was different. He was on his own, hitting the pavement with a digital image of the mural he’d planned.

He turned a corner one day and found the perfect wall — downtown, elevated, lit at night. The building was a hotel, and the owners turned him down. Bugs and hotels don’t mix, they told him.

“I thought, ‘Technically they’re not bugs,’ Peterson said. “But OK, we’ll leave that one where it lies,” Peterson said.

A lot of businesses had a similar answer — they would love a free mural, but not if it had feelers or claws.

“Then I started thinking, where else are there big open spaces?” Peterson said. “Well, there’s a lot of roof around. The idea came to me totally at random. I went on Google Earth and sure enough.”

The old armory, which houses the food court and Children’s Museum at the Seattle Center, is perfectly situated under the Space Needle. On an average summer day, more than 7,000 people take the elevator to the top.

“It’s a captive audience,” Peterson said. “The only thing you do at the Space Needle is look at stuff from above.”

After three months of consideration, Seattle Center gave him permission in mid-August — the hottest weeks of the year. He went to work immediately, scrubbing the seagull droppings and crud from the roof’s surface.

To complicate matters, he had to draw the mural slightly skewed to match the angle of the roof. He spent a few days sketching an outline with a fat lumber crayon, following a 10-foot grid system.

“It was exciting but it was stressful, because if I mess up something there’s no going back,” Peterson said. “What if I go up (to the Space Needle) and something is wrong, or I spilled a bunch of paint somewhere. It will just look bad forever.”

Painting took more than two weeks. He rode the Space Needle elevator 12 times to check his work. The guards only let him up certain times of the day. Otherwise, he had to pay $19 a trip.

The composite roof was made of gritty, multicolored material, which meant he couldn’t paint over his mistakes.

“It was really weird to do, but I had to trust it,” Peterson said. “That was the hard part: Trusting that what I was doing was right.”

Peterson hopes to paint a vertical 3-D mural with spray paint left over from the grant, possibly in Wenatchee.

“I’m very happy with the way it turned out, happier than I could have imagined,” Peterson said. “What’s interesting about this project is that it really finished the way I intended.”

Rachel Hansen: 664-7139

hansen@wenatcheeworld.com