Architecture firm FreeGreen, which uses an open-source model to offer and market free and low-cost green house plans, last week unveiled its Tiny House lineup, which features plans for three houses that are, well, really tiny.The temptation for some would be to build one of these houses on the basis of cuteness alone. In the candy bowl of second homes, these are barely bigger than breath mints. Each plan covers 525 sq. ft. of interior space, with one bedroom and one bath. The design styles are Tiny Traditional, Tiny Rustic, and Tiny Modern. The latter two include loft areas.Access to the plans is available to those who pay $19.95 for a one-year “premium” Free Green membership or $99.95 for a “professional” membership. FreeGreen says a premium membership includes downloads of premium house plans, access to two house plans in AutoCAD format, product discounts and 50% off plan customizations from FreeGreen. The professional membership includes access to FreeGreen’s details library and unlimited plans in AutoCAD format.When GBA first mentioned FreeGreen, on June 1, the firm was touting plans it had developed for a New England Colonial, now being built in Needham, Massachusetts, that will be a FreeGreen showcase home. The home’s owner, Rob Glazer, is blogging about the progress of the nearly completed project for the FreeGreen website.Fee-based plans offered on the site range in price from $20 to $2,500. FreeGreen makes money through advertising from the manufacturers, contractors, and other companies whose products and services are paired with FreeGreen plans.