Changing from 2D plot to 3D plot and to STL file

Hello everyone, I have these following codes: All of them creates a 2D plot, now I really want to create a 3D plot with Z: the thickness of plot XY. Then I want to convert it to STL file.

clc;
clear all;
close all;
% Input
R0 = 0.15;
a = 25*pi/180;
theta = 0:pi/1000:3*pi;
theta2 = theta + pi;
delta = pi/2;
%% Curl 1
R1 = R0*exp(a*(theta-delta));
X1 = R1.*cos(theta-delta);
Y1 = R1.*sin(theta-delta);
%% Curl 2
R2 = R0*exp(a*(theta-delta));
X2 = R2.*cos(theta);
Y2 = R2.*sin(theta);
%% Curl 3
R3 = R0*exp(a*(theta2-delta));
X3 = R1.*cos(theta2-delta);
Y3 = R1.*sin(theta2-delta);
%% Curl 4
R4 = R0*exp(a*(theta2 - delta));
X4 = R2.*cos(theta2);
Y4 = R2.*sin(theta2);
%% Extra plot (arc)
radius = R0*exp(a*(3*pi-pi/2));
a1 = pi/2;
b1 = pi;
h = 0;
k = 0;
t1 = linspace(a1,b1,3001);
X_arc1 = radius*cos(t1) + h;
Y_arc1 = radius*sin(t1) + k;

a2 = -pi/2;
b2 = 0;
t2 = linspace(a2,b2,3001);
X_arc2 = radius*cos(t2) + h;
Y_arc2 = radius*sin(t2) + k;

R5 = 0.05;
X5 = R5.*cos(theta);
Y5 = R5.*sin(theta);
%% Plot
figure(1);
plot(X1,Y1, 'k', 'LineWidth', 3); hold on
plot(X2,Y2, 'k', 'LineWidth', 3); hold on

P1 = plot(X_arc1, Y_arc1, 'k');
set(P1,'linewidth',3);
axis([h-radius-1 h+radius+1 k-radius-1 k+radius+1]) 
axis square; hold on;

plot(X3,Y3, 'k', 'LineWidth', 3);hold on
plot(X4,Y4, 'k', 'LineWidth', 3);hold on
plot(X5,Y5, 'k', 'LineWidth', 3); hold on

P2 = plot(X_arc2, Y_arc2, 'k');
set(P2,'linewidth',3);
axis('equal');
title('Two-arm equiangular spiral antenna', 'fontsize',14, 'fontweight','bold');
hold on
%% Filling with black color
patch([X1; flipud(X2)], [Y1; flipud(Y2)],'k');
patch([X3; flipud(X4)], [Y3; flipud(Y4)],'k');

X_arc1_bonus = horzcat(X_arc1, -4, -2.2, -2, -1, -0.3);
Y_arc1_bonus = horzcat(Y_arc1, 0.8, 2.2, 2.6, 3, 3.2);
fill(X_arc1_bonus, Y_arc1_bonus,'k');

X_arc2_bonus = horzcat(X_arc2, 4, 2.2, 2, 1, 0.3);
Y_arc2_bonus = horzcat(Y_arc2, -0.8, -2.2, -2.6, -3, -3.2);
fill(X_arc2_bonus, Y_arc2_bonus,'k');