The money to renovate and expand it is mostly raised. The preliminary drawings of fancy new exhibits and play space are cool and plentiful. But what begins this weekend at the Children’s Museum of Minnesota may be the most important piece of its $28 million reinvention.

Starting Saturday and running through May 10, the museum’s foremost experts — kids themselves — will help design a range of new exhibits meant to stimulate young imaginations.

By playing in two new prototype exhibits — “Creativity Jam: Make” and “Creativity Jam: Imagination” — children and their parents will put the concepts to the test and provide feedback for how to improve final designs of the museum’s coming renovation.

In short, the museum is looking to give kids more freedom and space to simply play by using their imaginations to create their surroundings.

“There are many different types of play. All of it matters. The type where learning sticks is the type that involves both their minds and their bodies,” said Nichole Polifka, the museum’s director of learning and impact. “With the new museum, the experiences that we are putting together now focus on that purely child-driven agenda.”

On Friday, museum officials will provide a sneak peek of those prototypes and announce that they are 82 percent of the way to their $28 million fundraising goal; $14 million has come from state bonding and about $9 million more from donors such as 3M, Best Buy and the city of St. Paul.

The next fundraising step will be to seek federal tax credits as well as approach patrons, fans and longtime supporters.

The money will be used to add a cafe and a build a four-story glass addition to the museum’s front that features a climber with slides and netting. Existing space will be reconfigured to add a skyway-level box office, move administrative offices and improve traffic flow throughout the building.

All of it will dramatically remake the museum visually and schematically, said Bob Ingrassia, vice president of external affairs. The project will add 9,000 square feet overall, boosting exhibit and visitor space by 34 percent. The new museum will feature nine new exhibits.

“It really is reimagining the entire Children’s Museum of Minnesota,” Ingrassia said.

The prototype exhibits opening Saturday offer very different experiences. The exhibit “Imagination” allows kids to take abstract objects to create their own reality. The idea is to inspire kids to exercise their imaginations without preset boundaries.

In the other prototype, “Make,” children will find a workshop where they can use real world tools to create and design projects to take home. The materials and tools used could change several times during a year to provide for unique experiences. Finished versions of both prototypes are expected to become permanent exhibits — with design help by the kids and their parents, said Michelle Blodgett, exhibit developer.

“We’re really putting an exhibit into our visitors’ hands,” she said of the Imagine prototype. “We’re able to shape it as we go along, which is really exciting.”

Other preliminary ideas for the exhibits include:

• Air & water play areas where kids manipulate ramps, pipes and hoses.

• A larger exhibit for kids 3 and under, featuring ramps, stairs, light play and water play.

• An adventure gallery featuring a carpet skate area and laser “ninja training.”

Polifka said that kids today don’t have many opportunities to let their imaginations shape their play. Society is very organized, she said, and focused on instant gratification through games, apps and toys. Creativity is a skill, and through exhibits that encourage kids to use their imaginations, the museum intends to “highlight, immerse, support these essential skills.”