|[<-'*/]^[\*'->]| ):\<^/A]H[A\^>/:( |[<-'*/]^[\*'->]|

1. symmetrical-text.js

function generateSymmetricTextLine() {
    const selfSymmetricChars = "*#^!+=-.':oO08|HAIX_WMVT";
    const chars1 = ">>><<</\*^:_.-'|!~)()()][[{}{";
    const chars2 = "<<<>>>\/*^:_.-'|!~()()([]]}{}";
    const maxWidth = 10;
    const maxNumChars = maxWidth - 2;
    const numChars = maxNumChars - Math.floor(Math.random() * 5);

    let string = selfSymmetricChars[~~(Math.random() * selfSymmetricChars.length)];
    for (let i = 0; i < numChars; i += 1) {
        let leftChar, rightChar;
        if (Math.random() < 1 / 5) {
            let randomIndex = Math.floor(Math.random() * selfSymmetricChars.length);
            leftChar = selfSymmetricChars[randomIndex];
            rightChar = selfSymmetricChars[randomIndex];
        } else {
            let randomIndex = Math.floor(Math.random() * chars1.length);
            leftChar = chars1[randomIndex];
            rightChar = chars2[randomIndex];
        }
        string = leftChar + string + rightChar;
    }
    return " ".repeat(maxWidth - numChars) + string;
}
var result = Array(100).fill().map(generateSymmetricTextLine).join("\n");
console.log(result);

2. symmetrical-text-original.gml

var chars0,chars1,chars2,str,str2,rnd,numChrs,i,sp,spp,c;
chars0="*#^!+=-.':oO08|HAIX_WMVT";
chars1=">>><<</\*^:_.-'|!~)()()][[{}{";
chars2="<<<>>>\/*^:_.-'|!~()()([]]}{}";
chars1=chars1+chars1+chars1+chars1+chars0;
chars2=chars2+chars2+chars2+chars2+chars0;
str2="";
sp=0;
spp=sp;

for(i=0; i<100; i+=1){
	str=string_char_at(chars0,random(string_length(chars0)));
	numChrs=random(5)+3
	repeat(numChrs){
		rnd=random(string_length(chars1))
		char1=string_char_at(chars1,rnd);
		char2=string_char_at(chars2,rnd);
		str=char1+str+char2
	}
	/*
	sp=round((cos(i/10)+0.5)*5);
	c="|";
	if(spp<sp)c="\";
	if(spp>sp)c="/";
	str2+=string_repeat(" ",10+sp)+c+nl;
	spp=sp;
	*/
	str2+=string_repeat(" ",10-numChrs+sp)+str+nl;
}
print(str2);
clipboard_set_text(str2);

3. symmetrical-text-direct-port.js

var chars0,chars1,chars2,str,str2,rnd,numChrs,i,j,sp,spp,c;
chars0="*#^!+=-.':oO08|HAIX_WMVT";
chars1=">>><<</\*^:_.-'|!~)()()][[{}{";
chars2="<<<>>>\/*^:_.-'|!~()()([]]}{}";
chars1=chars1+chars1+chars1+chars1+chars0;
chars2=chars2+chars2+chars2+chars2+chars0;
str2="";
sp=0;
spp=sp;

for(i=0; i<100; i+=1){
	str=chars0[~~(Math.random()*chars0.length)];
	numChrs=~~(Math.random()*5)+3
	for(j=0; j<numChrs; j+=1){
		rnd=~~(Math.random()*chars1.length);
		char1=chars1[rnd];
		char2=chars2[rnd];
		str=char1+str+char2;
	}
	str2+=" ".repeat(10-numChrs+sp)+str+"\n";
}
console.log(str2);