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The Little Britain star told BBC News that he and Walliams are to play a number of different characters in the new project.
He said he researched the film by looking at actors such as Mike Myers and Eddie Murphy, both of whom are known for appearing in various different roles in movies.
"We've got an idea that excites us that we hope will appeal to audiences in lots of different countries," he said.
"The two of us will play five or six characters that will go around together, so it'll be technically very challenging."
He added: "As our audience on TV are used to seeing us playing different characters, we thought it would be interesting to make a movie where we all play lots of characters and have scenes where they all interact."
The project, which has yet to be given the green light, is being developed by Ben Stiller's Red Hour production company for DreamWorks.
Lucas added that he is also "very excited" by his part in Tim Burton's adaptation of Alice In Wonderland, in which he will play both Tweedledum and Tweedledee.
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