Something to think about?most soapers like a bar around 3-1/2" wide or long, by around 2-1/2" tall, by 1" to 1-1/4" thick. A bar this size, depending on the thickness, will weigh in about 4-1/2 to 5-1/4 ounces after a good 5 to 6 week cure.
I AM an old timer. LOLDo you have access to even a hand saw? Like the old timers.. Many hardware, lumber stores will cut your wood for free.