Diamond
In a diamond, every word has odd length. Here are two 11-diamonds, one with the same words across and down, and one double:
Double:
M M
PER RIP
PAGER RESET
PHRASED DEICERS
PARALEGAL COSTARICA
MEGALOMANIA WINTERSPORT
RESEMBLED GUERRILLA
REGALES TRAINED
DANES STATS
LID EGO
A E
In a hollow diamond, the size of the hollow section should be such that the four longest words form a square.
D
RAS
FETAS
MATINEE
NONEVENTS
SETTLESDOWN
NEURAL TINIER
MOTRIN NIPPER
FANTAN CELLED
RETELL SUEDED
DATIVE SAPPER
SANEST FUSION
SENDIN SILENT
ETONIC SARTRE
SWIPES FIRERS
NEPLUSULTRA
RELEASERS
REDPINE
DEPOT
DEN
R