It depends on whether you want the hat crown to actually fit on the head or as small percher. Full size crown means you can tip a dome up side down to block but stabilise in cake tin with bubble wrap while blocking if making crown and brim separate to join later. If you are making all in one there are cr/brim boater sets available - chat to Darryll Hat Blocks Australia. For percher style with small crown19- 20" if you do not have a childs dome block to invert you would need to purchase a small flat tipped crown block for the boater crown. Again turn your cartwheel brim over to block the boater brim = perfectly flat - drill holes for collar to sit. (Not all the way through or pins will disappear on you forever) Depth of crowns are very small - 6cm is current trend but some accentuate it with 10 - 12 cm height and wider brim. Hope this helps. Elaine
Thanks Elaine. This is a great help! I will try turning the dome upside down.