var Foo = module.exports = function () {

    var values = { type: 'foo', prop1: '', prop2: '' };

    function model() {}

    model.init = function(val) {
        _.extend(values, val);
        return model;
    }

    model.store = function(cb) {
        db.insert(values.type, values, cb);
    }

    model.prop1 = function(val) {
        if(!arguments.length) return values.prop1;
        values.prop1 = val;
        return model;
    }

    return model;
}

var foo = Foo();
foo.init({prop1: 'a', prop2: 'b'}).store(function(err) { ... });

var Foo = module.exports = function () {

    var values = { type: 'foo', prop1: '', prop2: '' };

    function model() { this.extend(base); }

    model.prop1 = function(val) {
        if(!arguments.length) return values.prop1;
        values.prop1 = val;
        return model;
    }

    return model;
}

/** require your db and underscore varialbles etc.. **/

module.exports = function(values, base) {
    var model = typeof base == 'function' ? base : function() {};

    model.init = function(val) {
        _.extend(values, val);
        return model;
    }

    model.store = function(cb) {
       db.insert(values.type, values, cb);
    }

    return model;
}

var Foo = module.exports = function () {

    var values = { type: 'foo', prop1: '', prop2: '' };

    var model = require('/path/to/model.js')(values);

    model.prop1 = function(val) {
        if(!arguments.length) return values.prop1;
        values.prop1 = val;
        return model;
    }

    return model;
}

var Foo = module.exports = function () {

    var values = { type: 'foo', prop1: '', prop2: '' },
        model  = function() { ...something here... };

    require('/path/to/model.js')(values, model);

    model.prop1 = function(val) {
        if(!arguments.length) return values.prop1;
        values.prop1 = val;
        return model;
    }

    return model;
}