I'm not sure if they can do a real wigwam or not.  The key ingredient is birch bark.  I know birch trees have a bark that peels particularly easily making the large panels to construct the wigwam.  I'm not sure aspen bark would work as well.  However, apparently aspen and birch are pretty similar:<br/><br/>http://www.ehow.com/about_6368798_difference-birch-trees-aspen-trees.html (http://www.ehow.com/about_6368798_difference-birch-trees-aspen-trees.html)<br/><br/>Maybe Mrsjaz our expert on all things plant could give us her opinion on the bark.  If not, they could still do the grass house although from the description you posted the grass house isn't too good at keeping out the cold.<br/><br/>After looking over the process of making brick, I'll agree with you on log cabin.  They can get a wigwam or grass house built in a couple of days.  A log cabin in a couple of weeks.  I think a brick house would take months.  Bethany will probably want a kiln at some point for firing pottery.  Once they have a kiln they can produce bricks as well, but it will take a lot of brick to make a home.  That might be a year or more long project to be worked on in their spare time.<br/><br/>Turns out making adobe bricks is easier because they don't have to be fired.  They just dry in the sun.  The process looks quite doable:<br/><br/>http://desertphile.org/adobe/brick.htm (http://desertphile.org/adobe/brick.htm)<br/><br/>The summers will be dry enough, but they also need to be hunting, farming and putting away food for winter.  They can't spend all their time making bricks and building.  I think that ultimately the adobe house, with its 10" thick walls is superior to the log cabin in terms of comfort, fire safety and security, but it will also take longer.  A one room shack 15'x15'x8' would take 1,248 bricks.  Maybe they could make a one-room shack over the summer, but they could make a much larger log cabin in a fraction of the time.<br/><br/>Also unlike the wig wam, log cabin, grass house, etc, they probably need someone who knows the process.  Hopefully Bethany with her knowledge of pottery will know about bricks both regular and adobe.<br/>