Otdfbt

I have a few dozens of letters that I want to use inside document without auxiliary symbols (as a plain text).

How should I tune up latex for it?

I.e. As I see babel package allows to solve the same problem with a predefined sets of letters (usepackage[russian, german, french]babel). I want to have a kind of a set with other letters.

Thank you for an answer.

You can do almost all of those characters with pdflatex (I changed the Cyrillic A and a into the Latin ones). The only ones not covered in the default setup are Ŧ and ŧ, but it's not difficult to add suitable definitions for them.

documentclassarticle
usepackage[T1]fontenc
%usepackage[utf8]inputenc% not needed in recent LaTeX
usepackagegraphicx

DeclareUnicodeCharacter0166barredT
DeclareUnicodeCharacter0167barredt

DeclareRobustCommandbarredTbarredTt0.50.051.5T
DeclareRobustCommandbarredtbarredTt0.401.15t
newcommandreducedhyphen[2]%
 raisebox#1exscalebox#2[0.5]-%

newcommandbarredTt[4]%
 begingroup
 vphantom#4%
 ooalign%
 #4cr
 hidewidthkern#2emreducedhyphen#1#3hidewidthcr
 %
 endgroup


begindocument

newcommandcharlist%
 parnoindent
 A a Á á Ä ä Å å B b C c Č č D d Đ đ E e É é Ë ë Ě ě Ę ę F f 
 G g Ĝ ĝ H h I i Ï ï Ǐ ǐ Į į J j K k L l M m N n O o Ó ó Ö ö 
 Ô ô Ò ò P p R r Ř ř S s Ŝ ŝ Š š T t Ŧ ŧ U u Ú ú Ü ü Ų ų Ŭ ŭ 
 V v Y y Z z Ž žpar


charlist
textbfcharlist
textitcharlist

enddocument

I don't really understand what needs to be tuned up.

documentclass[twocolumn]article
usepackagemwepage
usepackagefontspec
usepackagelibertine
begindocument
noindent А
а
Á
á
Ä
ä
Å
å
B
b
C
c
Č
č
D
d
Đ
đ
E
e
É
é
Ë
ë
Ě
ě
Ę
ę
F
f
G
g
Ĝ
ĝ
H
h
I
i
Ï
ï
Ǐ
ǐ
Į
į
J
j
K
k
L
l
M
m
N
n
O
o
Ó
ó
Ö
ö
Ô
ô
Ò
ò
P
p
R
r
Ř
ř
S
s
Ŝ
ŝ
Š
š
T
t
Ŧ
ŧ
U
u
Ú
ú
Ü
ü
Ų
ų
Ŭ
ŭ
V
v
Y
y
Z
z
Ž
ž
enddocument

cm-unicode has all the glyphs (not Latin Modern):

documentclassarticle

usepackagefontspec
setmainfontCMU Serif

begindocument

АаÁáÄäÅåBbCcČčDdĐđEeÉéËëĚěĘęFfGgĜĝHhIiÏïǏǐĮįJjKkLlMmNn OoÓóÖöÔôÒòPpRrŘřSsŜŝŠšTtŦŧUuÚúÜüŲųŬŭVvYyZzŽž

enddocument 

In XeLaTeX or LuaLaTeX, usepackagefontspec to enable all Unicode characters. If you use the babelfont command after loading babel, this will also load fontspec. Make sure the font you select contains all the characters you need. For example, you mentioned Russian and the default Latin Modern Roman does not contain Cyrillic, but Computer Modern Unicode does, so you might write it this way:

documentclassarticle
usepackagebabel
usepackagefontspec

babelprovide[import=ru, main]russian
babelprovide[import]german
babelprovide[import=fr]french

% Versions of babel prior to 2019 incorrectly ignored all default features.
% As a workaround, you could specify them as options.
defaultfontfeaturesScale = MatchLowercase
babelfontrm[Scale=1.0]CMU Serif
babelfontsfCMU Sans Serif
babelfontttCMU Typewriter Text

begindocument
otherlanguagegermanFrauenfußball

otherlanguagefrenchfootball féminin

otherlanguagerussianженский футбол
enddocument

(You can add the Language=Default font feature to any of the fonts to suppress the harmless error message about a language not being “available with” a script.)

In PDFLaTeX, start by setting the correct font encodings for the glyphs you use, if babel doesn’t already. Western European languages use T1 and Russian uses T2A or X2. You generally also want to usepackagetextcomp to get other commonly-used symbols from the text-companion encoding. When you usepackage[utf8]inputenc (which has been the default since the spring of 2018), LaTeX will understand any Unicode characters from the standard encodings that you select.

If you need any other Unicode characters that you cannot support this way (because you need to load them from another font or fake them with a command), you can declare them with the newunicodechar package, e.g. newunicodechar🄯reflectboxtextcopyright.