I think you may be able to tell from the first photo here: https://twitter.com/jdhoek/status/881243775288389632 https://twitter.com/jdhoek/status/8812437752883

I think you may be able to tell from the first photo here: https://twitter.com/jdhoek/status/881243775288389632 https://twitter.com/jdhoek/status/881243775288389632 And the second photo here: https://twitter.com/jdhoek/status/876126132734656514 https://twitter.com/jdhoek/status/876126132734656514 So beaks at the front and back, with trapezoidal blocks that fit in between. The shelves rest on those blocks.