Well... You can take a basic six color hand press and load it with three 48 x 48 plattens any do a belt style all-over. This method works well, but has minimal registration ability and is messy, ie having to put kraft paper down, double glue shirts etc.
Or you can do as we did and purchase hundreds of thousand if dollars worth of equipment, then get a clean and tight registration, but have enourmous machines, no money, and a pain in the *** to change plattens..... But able to produce insane amounts of product.
There are a few various options between but my recomendation would be to start with a handpress, then do the MAJOR upgrade... When companies invest in halfway equipment it hurts them.... Also the hand press is amazing option because so little risk, 5k and your done. I would run with that as we did until you are comtracting so Many all-overs that it makes sense to purchase.
J