Are you a Spanish speaker? Usually when I want to make a voicebank, I see the Wikipedia page of that language. Here's for Spanish:
en.wikipedia.org
From that page, I made a simple list of what to record:
a e i o u
bab beb bib bob bub (Bestia)
BaB BeB BiB BoB BuB (beBé)
dad ded did dod dud (cuanDo)
DaD DeD DiD DoD DuD (arDer)
faf fef fif fof fuf (Fase)
gag geg gig gog gug (Gato)
GaG GeG GiG GoG GuG (triGo)
jaj jej jij joj juj (aYuno)
dZadZ dZedZ dZidZ dZodZ dZudZ (Yermo)
kak kek kik kok kuk (Kilo)
lal lel lil lol lul (Lino)
LaL LeL LiL LoL LuL (LLave)
mam mem mim mom mum (Madre)
nan nen nin non nun (Nido)
JaJ JeJ JiJ JoJ JuJ (Ñandú)
NaN NeN NiN NoN NuN (ciNco)
pap pep pip pop pup (Pozo)
rar rer rir ror rur (caRRo)
4a4 4e4 4i4 4o4 4u4 (caRo)
sas ses sis sos sus (Saco)
TaT TeT TiT ToT TuT (Cereal)
tat tet tit tot tut (Tamiz)
tSatS tSetS tSitS tSotS tSutS (CHubasco)
vav vev viv vov vuv (aFgano)
xax xex xix xox xux (General)
zaz zez ziz zoz zuz (iSla)
SaS SeS SiS SoS SuS (SHow)
You can see the word reference inside the parentheses, and the exact letter is capitalized. I'm not a Spanish speaker, if you think some of the letter is pronounced the same, you can just omit the line. Since it's a CVVC, make sure to really hold the consonants when ever you can hold it. Take M for example, record it like "mmmaaammm". You don't have to hold it for letter like P, because you can't.