The two-story treehouse is in place, the beaver lodge has been installed, and the riverbed is growing. Nearby, volunteer Susan Carlisle is grappling with the Nature Trails area’s turtle, rubbing it down with a sandpapery pad. “I’m roughing it up so it can take a coat of paint,” she explained. “Got to get the museum open.”

Carlisle is referring to the Maine Discovery Museum, where contractors, employees and dozens of volunteers are hard at work to ready the facility for its Feb. 10 grand opening in the Freese’s building on Main Street in Bangor.

Organizers of the grass-roots effort to build a children’s museum have said all along they expect it to be popular, drawing 70,000 visitors a year to the downtown.

Even before the museum opens, 410 people have signed up for an annual membership, and staffers have scheduled 47 birthday parties as well as field trips for more than 4,500 schoolchildren.

It was one thing to watch elements of the exhibits under construction at Display Concepts Inc. in Trenton. It’s quite another to watch Nature Trails and Booktown and Mission Discovery take shape in the museum.

“Hey, the tongue’s here,” Natalie Whitehouse said one morning last week.

Whitehouse, who is director of marketing and development for the museum, was walking through the Body Journey area on the second floor – past the giant head, around the humongous heart, by the intestine and underneath the massive bones draped over the wall.

The exposed joint was the knee, just waiting for the kneecap, workers explained. On the other side of the wall, in the “doctor’s office,” the ankle and foot bones were visible.

“Every day, it’s amazing how much new stuff comes in,” said Sean Faircloth, executive director of the museum.

The red-and-yellow gas pump and motorcycle for Condon’s Garage are on site, ready for youngsters who want to rev the engine to bring alive Robert McCloskey’s “One Morning in Maine.”

The items are part of Booktown, where Zuckerman’s Barn is nearly ready for Wilbur, the pig in “Charlotte’s Web.” Not far away is the lighthouse from “Keep the Lights Burning, Abbie.”

In another room, bright green walls, a colorful little house with mouse holes near the floor will fascinate toddlers who love hearing “Goodnight Moon.”

Around the corner are a writer’s cottage for a puppet theater and the library from Barbara Cooney’s “Miss Rumphius.”

Booktown is rather a special exhibit for a children’s museum, according to Reb Haizlip, the Memphis designer who collaborated with North Carolina designer Jeanne Finan on the exhibits.

“I’ve never seen that done before,” he said on one of the pair’s trips to Maine to present their work. “That’s really unique. It’s going to be fun for the kids, but I think the adults will love it.”

The entrance to Booktown will feature a “walk of fame” where one tile will be added each year in honor of an author who will participate in a children’s literature festival in the fall.

Carpet with a road pattern will lead the way to Passport to the World, featuring a Peruvian schoolroom and a marketplace from Ghana.

The Australian corner offers an outback tent and duckbilled platypus, but certainly youngsters will want to visit the cave to test the heat-sensing wall, which changes color when a hand is placed upon it.

Like the other 60-plus interactive exhibits built by Joe Rizzo’s crew in Trenton, this one is educational as well as fun. The handprints are intended to illustrate aboriginal art.

Speaking of art, one of the busiest spaces in the museum may be the Artscape classroom, where summer camps and after-school programs will be held.

Next door in Sounds Abound, kids can sing nursery and holiday songs in the karaoke room, while parents might try some Beatles or a little Cole Porter.

Budding scientists will view the night sky in the Constellation Capers planetarium section of Mission Discovery, make sculptures on a magnet table or play Bernoulli basketball, using air to keep the ball aloft.

Three children can manipulate robotic arms to hand things to each other, varying degrees of skill creating more special effects.

“That fosters teamwork,” Faircloth explained.

His young sons have tried out several of the museum pieces, including the “frozen shadow” wall, which uses a strobe light to freeze the youngster’s movements.

One room in the museum has an unusual view – the Standpipe, Sawyer Arena, a bit of the creative playgrounds.

That’s because the murals for Head Down Baseball Diamond, done in an impressionistic style, were based on a photograph of Mansfield Stadium, the Little League field off Union Street.

The exhibit honors Maine athletic figures as well as Bangor authors Stephen and Tabitha King, who built Mansfield and also donated $900,000 to the museum.

The Maine Discovery Museum has received significant support from the city of Bangor as well, Faircloth said. The City Council voted to provide the 22,000 square feet of space in the Freese’s building, contributing the $1.25 million to renovate the space to “white box” condition.

That amount and the King money provided a good start to the more than $4 million the capital campaign committee has raised so far under the chairmanship of Susan Carlisle.

Sponsorship opportunities are still available for specific items, Faircloth said, and the donor wall won’t be installed until March, in an effort to include those who are still making pledges.

The museum has begun to do mailings to schools, and Andrea Stark is working on educational offerings for the facility.

Faircloth expects people to find out about the museum by word-of-mouth, and from the Web site at www.mainediscoverymuseum.org.

The executive director said he was very pleased with the site, which was donated by Prexar and designed by Scott Traylor, a Web developer with the company.

The site will walk people through the museum, Faircloth said, and will enable people to sign up for memberships and conduct other business with the museum over the Internet.

There are two levels to the site, Whitehouse said, one for grown-ups, and, for children, one with more special effects.

Regular hours for the museum will be 9:30 a.m.-5 p.m. Tuesday, Wednesday, Thursday and Saturday; 9:30 a.m.-8 p.m. Friday; 11 a.m.-5 p.m. Sunday; closed Mondays, except school holidays. Grand opening is Feb. 10-11, with previews for founding members the week before.

General admission is $5.50. For groups registered in advance, tickets are $3 for children, $2 for chaperones, and free for teacher chaperones. For information on services or on volunteering for the museum, call 262-7200.